It's not 100% clear if you did repartition/reformat. If you did, it should have solved the issue
as there would not have been any Linux left (unless you formatted the wrong partition) and there is a good chance that Windows would not boot after that (Grub error).
The error message that you got is generated by your monitor.
You can cycle through the configured resolutions by pressing <ctrl><alt><+> (control-alt-plus). This could have solved the issue temporarily (need to do it after each restart of the X-server)
This could have been / can be solved permanently by reconfiguring your X-server correctly. If you press <ctrl><alt><Fx> (x being a number between 1 and 6) while in the graphical environment, you should be taken to a console screen where you can login and reconfigure the X-server.
Your 125G is not lost. Either re-install Linux on it (the installer should find the 'lost' partition and allow you to use it) or if you want it back in Windows, you can use the disk manager (or whatever it's called) and reformat it.