When you applied for Aadhaar Card then you have been received acknowledgement slip. This slip at the top contains 14 digits enrolment number and the 14 digit date and time of enrolment. If we combine both then this is 28 digits and it is called a temporally Enrolment ID (EID). If Aadhar Card Acknowledgement Slip lost and you do not know the Enrolment Number or EID then there is only two option either call on Toll Free number or email them for this help. Share your issue with them, you may ask about the enrolment number from them. They will try to search your data and if they find enrolment number they can let you know status of Aadhaar Card also.
You may write the issue and send on below Address -:
Unique Identification Authority of India (UIDAI)
Government of India
3rd Floor, Tower II
Jeevan Bharati Building
New Delhi – 110001.
You can email or call on Toll Free Number as mentioned below.