HOW DO I Find out if I am a beneficiary in someones will and I am not sur who it is?

Is the someone you don't know, alive or dead?

Or don't you know?

And why do you suppose that someone you don't know would make you a
beneficiary in their will?

Do not begin a sentance with AND,  did you not learn propper gramer ?

Would you have got an Email saying that someone has left you a load of cash ?

Good thinking, Jerry ...

Could be a scam.

If you received a letter or an email from a person or organization
that says that it knows of money left in your favor, but wants you to
pay them something, it is likely to be a scam.

Unclaimed funds in the U.S. eventually are held by each state.  The
information can be accessed by anyone free from their websites. 
However, there are outfits that do this and find the people, and ask
for a commission.

If you can give us more information, we can probably help you a bit further.