If you're sure you can't locate "hammer.exe" in "Steam\steamapps\common\Team Fortress 2\bin\", then try verifying the integrity of game files through Steam. It should detect missing/corrupted files and will proceed to download the original ones.
If this is your first time logging in after the migration (Feb 8, 2022), you must reset your password to log in. Follow this guide if you're having trouble