Is there a way to get your btc wallet back if it is suddenly gone?
Only if you have a backup, or can recover the wallet from your computer.
I have my password and seed but I can't find my old wallet.
If the seed belongs to your wallet, you can restore it.
I just realized this is a different wallet I created (using the same password).
Your password protects the wallet on your computer, the seed restores the wallet. The password is useless without the wallet.
What happened to my original wallet? I think I just lost $900 sending it to a wallet I can no longer find.
Where did you get the address you sent your Bitcoins to, if you didn't get it from your wallet?