How can I save my progress? I tried to save it through the pause menu, but it didn't, and I've lost my progress. Did anyone have the same problem? How can I fix it?

SS2 or SS1?

SS1

inability to save was a problem with the old, pre-KEX build of the game, are you maybe playing that?

I am playing enhanced edition

yes, but are you playing the source port edition? do you have opengl and d3d in your video rendering options (and many resolutions)?

Porly I don't know. How can I find out?

check the video options.

In video resolution options there was Direct3D, and yes, there is opengl

so it's the KEX port. well, no ideas really, try to uninstall, and maybe reinstall into a different location. the old issue where the game would not work properly if the windows username contains special characters should be resolved, but you still can try to create a different windows user with no special characters and try to install the game under that profile.

or you can try the Shockolate opensource port.