This is a very interesting topic I too have a similar experience losing a wallet.dat I just don't try to recover it since I only had a few coins on it,what I do is to always create a duplicate in my cloud storage,but I also would like to know how to recover your wallet.dat if you accidentally or not delete it..
Dont hijack topics.
To be clear I have a wallet.dat file with a password, that I do in fact remember, on a flash drive. Do I just download a program and copy and paste it?
The wallet.dat must be in the data directory[1] when you start the wallet. It will need some time to sync and verify the currently ~100 GB blockchain. Once thats done you can use the coins. If you moved to a more powerful machine you should set a new password.
[1]
https://en.bitcoin.it/wiki/Data_directory#Default_Location