If you use an application that forcefully changes your screen resolution to something you’re not happy with, you can easily change back to your native (or, any) resolution by using the xrandx command from your terminal window.
Start up your terminal and type in: xrandx
The system will return your current resolution -marked by an asterisk- and any other resolution that your monitor can go up or down to.
In order to set your resolution, type: xrandx -s 1024×768 (or, any other resolution you want to change to. Just make sure that your monitor supports it).
