How do I get google play back to sys app without being able to access any apps on google play?

How do I get google play back to sys app without being able to access any
apps on google play?

After rooting my galaxy s, I deleted google play. I have now downloaded it
but I cannot get it back to sys app and it forcecloses every time I try to
open it. I can't download anything from google play to help me solve the
issue. Please help! Thank you!