How to know if I was eligible for the recovery rebate?Is this $5000 stimulus real if so how to claim it? And what if I already filed my taxes?

There is no $5000 stimulus.   

The recovery rebate credit was on returns for 2020 and 2021.   It is too late for 2020---the deadline was May 17, 2024 for that one.   The deadline for the 2021 stimulus ---recovery rebate credit-- is April 15, 2025.  

Look at your online account with the IRS to see if they sent you $1400 in 2021.

https://www.irs.gov/payments/your-online-account

If you could be claimed as someone else's dependent in 2021, you are not eligible for the payment.

If you were eligible and did not receive a payment  from the IRS, the other way to get the payment is to amend your 2021 return to use the recovery rebate credit before April 15, 2025.   If you did not file a 2021 return at all, then prepare one and mail it in.

2021

https://www.irs.gov/pub/irs-pdf/i1040gi.pdf

Here is the IRS 2021 Form 1040
https://www.irs.gov/pub/irs-prior/f1040--2021.pdf

or if you want bigger type use 1040SR for Seniors,
https://www.irs.gov/pub/irs-prior/f1040s--2021.pdf

And 2021 Instructions
https://www.irs.gov/pub/irs-prior/i1040gi--2021.pdf

2021 Tax and EIC Tables
https://www.irs.gov/pub/irs-prior/i1040tt--2021.pdf

Sch 1 : https://www.irs.gov/pub/irs-prior/f1040s1--2021.pdf
Sch 2 : https://www.irs.gov/pub/irs-prior/f1040s2--2021.pdf
Sch 3 : https://www.irs.gov/pub/irs-prior/f1040s3--2021.pdf