Are you sure about changing wallet file name with a new one? Because if I try to write another name, it tells file not found.
Yes, you can do that. Itested it and it works.
Here is the first screen that I get with my encrypted wallet:
if you change the wallet name and choose a new name:
it says:
This file does not exist.
Press 'Next' to create this wallet, or choose another file.
If you click next, you will be able to restore your wallet from seed:
@OP, are you using Electrum? if yes, then follow the above steps. If not, please tell us what wallet you are using.