What version of Electrum did you installed? Beware on fake Electrum 4.0 wallet.
Are you using windows OS? if yes try this method below this is mostly work if the file is overwritten.
- First, go to the Electrum folder it mostly located to C:\Users\admin\AppData\Roaming\Electrum
- Now open wallet folder then look for default_wallet.dat
- Right the default_wallet.dat and click restore the previous version
- Now the file properties will pop up then choose the old Default_wallet.dat.
I got this method from here
https://www.youtube.com/watch?v=PED-F3_7hOcSo credit to him if this method work.
If not try to do a system restore this is working sometimes to me if I accidentally update some software in my PC. So I think it might also work on restoring your old wallet and files.