People are panic and don't know how to sort out getting their Aadhaar Card even some of them waiting more than a year after Aadhaar enrolment process. Recent newspaper notifications issued by authorities saying, Govt. subsidies, scholarships and pensions shall not be released without providing Aadhaar linked bank accounts. Many are visiting Govt. offices like village, panchayat, tehsil or municipal offices to collect their Aadhaar letter and return vain or with insufficient guidance.
Here is the solution how to handle such situations properly: E-Aadhaar Letter.
First of all, stop worrying about not receiving your Aadhaar card. Use E-Aadhaar letter for places where asking Aadhaar card or Aadhaar number. If your Aadhaar enrolment is over and experiencing delay in receiving Aadhaar card letter, you may proceed one of the following methods:
1. You have access to internet connected computer
Keep ready your acknowledgement / resident copy of Aadhaar registration as the reference for further steps.
Visit www.uidai.gov.in and click "Check Your Aadhaar Status" from the right menu bar located under UIDAI Echo System > Residents. This page will direct to a form that asks your Enrollment ID with Date time stamp which is printed on your Acknowledgement / resident copy slip.
Screen shot given below shows the Aadhaar Status Check window on resident portal of UIDAI.

Before submitting the form you should fill the verification code shown just below the text field.
After a few seconds, the system will return a message whether your Aadhaar has been generated or not. If your Aadhaar letter has been dispatched to your address, it will mention the date of dispatch too.
If Aadhaar has been generated, next you to click the e-aadhaar link given under Main Menu of Resident portal. A new window with a form will display for receiving your data again. Fill all the fields properly and submit.
Now submit your mobile number for verification and you will receive OTP (One Time Password) as SMS on your mobile. You have to enter this OTP and submit the form.
How to Open Password Protected E-Aadhaar Letter
To protect your E-Aadhaar data, UIDAI transmitting it to you as a password protected pdf file. When you try to open your E-Aadhaar Letter, it will prompt for password. You have to enter password which is predefined by UIDAI. Here is how you can open E-Aadhaar PDF file:
Use your postal PIN code for opening the downloaded E-Aadhaar letter. (Old method)
Combination of the first 4 letters of English name in CAPITAL and the year of birth (YYYY) as password. See image given below for how to open password protected eAadhaar Letter:

Now your turn to take print out of this E-Aadhaar for your regular use. Note down the Aadhaar number and quote it where ever it may be requested. This E-Aadhaar is valid for opening bank account and all other identification purpose. On receiving your Aadhaar number, take it to your bank branch and get it linked to your bank account for Govt benefits.
2. You have no access to internet connected computer
If you don't have access to internet connected computer, take your Acknowledgement / resident copy slip to one of the public e-centre like Common Service Centers or Akshaya centre in Kerala or any internet cafe where printing facility provided and asked them to help for taking E-Aadhaar letter. There will be charge for this service including printing charge for the same.
Validating your E-Aadhaar letter
You may notice that your E-Aadhaar letter has a question mark on the signature validation area where there is a note saying, it is not validated. Click How to validate signature in order to get the instructions.
How much time it takes when it says aadhaar card is under generation?
When we talk about Aadhhaar card, there is no certain date or value or concerns with respect to citizens's curious questions. Even though, I have personally known some of my acquaintances and relatives who received their aadhaar card within a couple of moths, after their aadhaar enrollment.
During the Aadhaar card generation process, UIDAI authority seeks review / recommendations / approvals from various agencies who has involved in the particular person's aadhaar enrollment process. If there is more clarity or explanation required in this Aadhaar card quality check, the generation of Aadhaar card may get delayed another 2 to 3 months or even more! In this case, better to contact them over toll free phone number (1800-300-1947) and explain your concerns. If there is any reason for delaying it, they can trace it and may speed up the process for generation of your Aadhaar card.
Due to technical reasons, enrollment data may get corrupted or lost. In such cases you have to go for fresh Aadhaar enrollment process.
If you are in urgent need or unprecedented delay, contact them over toll free number given above once in a week basis.
Get your Aadhaar Card Number through Mobile SMS
What is OTP or One Time Password?
OTP or One Time Password is a temporary password generated by computer during an online transaction or request or submission happens through websites of banks, govt. departments, admissions etc.
Sometimes, OTP refers to SMS password too.
After submitting or request made by website form, system generates a random digits and send it as an SMS to the mobile number he/she registered with the website. It is an extra security feature provided to the customer as well as the institution preventing un authorized access to such sensitive data transmission.
SMS you have received during the process, contains the password that to be entered in to the box showing concerned webpage. If you enter exactly the same digits, your transaction or submission made successful and complete else system will ask to enter again. If you fail or not received SMS, you can't continue or complete the process or submission.
Some of the mobile operators are failed to deliver such SMS / OTP passwords instantly hence you can not complete transaction that requires OTP security. In this case you either have to change your mobile number or transfer your mobile number to another service provider using Mobile Number Portability (MNP). I had the same issue when I used Tata Docomo number hence I changed to different mobile service provider.