I fear "easybrowser cafe billing software" and gpEasy are two completely different things.
gpEasy is a Web Content Management System (CMS). They only share "easy" in their name.
If the software you installed locked you out of your (MS Windows) Operating System, try to start in Safe Mode (Windows up to ver 7: repeatedly hit F8 key at system startup, Windows 8+: press and hold the Shift key at system startup).
When in Safe Mode, uninstall the easybrowser software.
(You could also try to log in to Windows pressing Ctrl-Alt-Del at the Welcome Screen and kill your software using Task Manager but this will not always work)