Go to the location of your bitcoin-qt file -> Shift+Right click -> Open command window here -> bitcoin-qt -salvagewallet
It doesn't open a command window in Windows 10.
1. Click shift+r and then type "cmd.exe".
2. Locate the bitcoin-qt.exe file and copy the path at the top (where explorer shows the path, click that and you'll get text - you may need to double click).
3. run "cd "+[path you just copied]
4. *optional run "dir | grep bitcoin-qt.exe" (just check that it is there and you're in the right place)
5. run "bitcoin-qt.exe -salvagewallet" and it should run the salvage wallet command.
EDIT: just to check, when you ran the option above, you didn't select the bitcoin-qt.exe file before trying to open the console window did you? It has to run just in the main part of that folder, not in a specific path.
Alternative Method:
Open notepad++/notepad.exe and type "bitcoin-qt.exe -salvagewallet" and save that file as "bitcoin-qt.bat" n the same place as the bitcoin-qt.exe application. (ensure you change the type from ".txt" to "All Files").
Then just select this file in explorer and hit enter.
