Sorry for bothering but I am in great need of help...
There are basically 2 problems

1. I cant find any server but a line "Steam beta must be running......"
I have my beta participation to beta update but it changes nothing.
2. Whenever I try offline practice, it crashes at the same point at "loading resources". A pop-up of memory could not be read appear and close the game.

I have tried
1.Verifying game cache
2.Defragment
3.Re-installing the game
4.Re-registering all dll files
5.Deleting clientregistry.blob of steam
6.Deleting all prefetch files
7.Disabling background applications

None of the above works....
Please help me.

I'm not a long time Steam user, but in such case you should try to set beta participation to NONE - opt out to any beta testing. Valve are busy updating TF2 they may break the compatibility with beta version of Steam (I think).

Did you tried turning off anti-virus/anti-spyware or similar softwares? Some security software can interfere with Steam, try turning off them and try.

You can try to add -condebug to the TF2 launch options in Steam, then post the D:\program files\Steam\steamapps\<your steam account>\team fortress 2\tf\console.log to the Steam support forum. According to the Steam support forum posts I think you are not alone.