Messed up resolution

[AC Question]

Hello,
I wanted to set a lower screen resolution to gain more FPS in games on my Xperia M.
I got myself Resolution Changer PRO and googled myself a resolution to try. However, now I have a screen resolution as the size of a watch, and I was not able to change the density as the changes took place instantly and now I only have 1/6th of my screen available.

How can I undo this? If possible without flashing a new firmware or data loss.
My phone is rooted.

 

[FliP0x]

That's me, just registered. I managed to get my resolution back by luckily hitting the 'Enable' button to disable the changes.

Now what I'd like to know is some nice, "high-performance" Xperia M (4 inch) screen resolutions with density to use.