Does anyone know where I can find the game files for
The 7th Guest. I am using windows 10

Just to be clear - do you mean where the game files would be located on your hard drive if you have the game installed?

If so, let's wait for someone who is familiar with Windows 10.

Do you mean save files or game installation files?
Is your game a download or CD version?
Game and save location can vary with the publisher.

The game and its saves are probably in the same location in Windows 10 that they'd be in Vista/7/8. The install and save locations might vary according to where the game is from and what version it is, but probably not because it is Windows 10.

An old download of the GOG version (April 2013) put the saves in
C:\Users\<your-username>\AppData\Local\VirtualStore\Program Files (x86)\GOG.com\The 7th Guest

The GOG version is apparently using ScummVM for the game rather than DOSBox.
That means saves will not be compatible with the original game.

In order to use ScummVM I need the installation files. I downloaded the game from Steam. Your suggestion of where the files might be does not work. I have also checked with Steam but get no reply from them.

Someone posted that on Windows 7, the files can be found here:

C:\Program Files (x86)\Steam\SteamApps\common\The7thGuest

No idea if the files are in a similar location on Windows 10.

Thank you Marian for the help. That is where the files are.

You're welcome.