we are on fixed non taxable disability income so i am not going to file but i have been told i can only get my second ck is to file an income tax form 1040sr.  Is this right...i am so confused!

Yes, this is correct. You can still receive a refund for the second stimulus check never received. Here is how to report.

1. Log into turbo tax
2. Click on Federal Review 
3. Let's make sure you got the right stimulus amount>continue
4. Next screen asks Did you get a stimulus payment? Yes
5. Then a drop down will appear and this is where you enter your first and second round stimulus payments. I
6. If you did not receive your second check, you will report that you received the first round stimulus payment of $1200 and enter a 0 for the second round.