Is it even possible because I tried one method but I think it was for Beta 1 only so my WMP is now bricked.
Win7 RTM is shipped with WMP12 so why do you want to downgrade to ver 11? If you don't like WMP than use WinAMP or foobar instead.
Well, well, well. Should this be an order?! I don't like WMP 12 very much and I want 11, is something wrong with that?
Yep, your craaaaaaazy. Haha. I am not sure if WMP will easily let your downgrade, last I saw when someone tried, the WMP installer saw the newer version and then canceled itself since it saw the newer version. I could be wrong though, I have not tried it myself. If you have issues and it won't let you put on the WMP you want, I can recommend VLC. It's a clean uncluttered interface, no extra fancy bells whistles and skins crap, but it has all the video & audio codecs integrated into it, and will play just about any video or audio format you throw at it. It's also opensource/freeware, (no cr**ks, serials, loaders, SLICs lol) and is still actively developed and improved.
Anyway modifying important files will ruin your OS once a major update comes out and can also harm all the mediacenter stuff.
Windows 7 RTM, at least Ultimate lets you uninstall WMP 12, check add/remove programs (or whatever the new name is). I suppose you can uninstall it and then install 11...though it still beats me why you'd like to do that...if you want to run the whole interface just click the arrow with the 3 squares... Bloodbat