Overclocking gone wrong

Hello, everyone. Today I am here to bring you probably the stupidest thing you'll ever hear..

So, basically, I was trying to overclock my AMD Radeon HD 5450 2GB DDR5 without having a bit of knowledge of what I was doing. And so, I pushed the "high memory overclock settings (or something similar, it's the second option to tweak on)" to the limit and instead of testing it, I applied it. And so, my journey towards misery began. Whenever I attempt to launch an application, I began having a purple screen with red scratches alongside with artifacts, screen freezes which had an only fix, restart the system.

What I've tried so far:
1) I tried running the windows on the "last known good configuration", nothing.
2) I tried uninstalling the Catalyst Control Center and the GPU driver and reinstall them. Still nothing.
3) Disabling the GPU temporarily and tried to access the Catalyst Control Center to fix the mess I've made. It was unable to start since I disabled the GPU.
4) I tried System Restore, and when it finishes and it's supposed to boot, it gives me this message (or similar to it): "Windows was unable to boot due to some recent hardware change". I haven't had any hardware changes for a fair amount of time, but I believe that it is referring to the overclocking mess.

Right now, I have my GPU disabled and I am browsing my computer on 800x600 and this truly sucks. I can't really seem to find a fix for this problem even though it is common.

Any help would be very much appreciated. Thanks in advance!