i need to go back to high sierra (i have Cataina now)

Any apps that are 32-bit will not work with Catalina, you need to upgrade. If that's not feasible do you have a Time Machine backup with High Sierra you can use to restore your system.

Restore your Mac from a backup - Apple Support

If not, then you'll have to reformat the hard drive, loosing all your data if you don't back up before, and re-install High Sierra.

Do you have a Time Machine backup to Restore to/from?

If not…

https://www.imore.com/how-downgrade-macos

What programs?

Do you have a time machine backup from before you upgraded?