I cleared my data folder to make it lighter for the engin. Deleted some files, cleared windows basket, defragged HD. Yes, as the title are saying, I am.
Above has resulted I can't load any saves and start new game.
1.I have all bsa
2.my and default ini.- the same
3.with and without obse on board
4.with oblivion.esm only
I have GOTY edition, patched.
I'm planing to make the second installation and compare new and old one. But maybe is easier way to repaire my game ?

You are better of reinstalling, You erased the music, shaders, and video folders.
You may need to rename or delete your configuration settings for your game, This file is found in Users\"Your Name"\Documents\My Games\Oblivion - the file is also named Oblivion. I say to rename because you may need to transfer some of the older sttings like enable screen shots, and disabling border regions.

No,I did not. These folders still are there. I've erased not used esp files, TES4edit backups and text files from Data folder. This text file erasing I blame for my problem.

I looked at my data dir and see one important TXT. file......DLClist.txt. This file is there to tell Oblivion what DLC you have purchased and would be allowed to run. Other then that I don't see any crucial .txt files...well theres Credit .TXT...lol

As far as I know DLClist.txt isn't essential. In fact I don't even think it does anything.

Gonna test this...BRB

Yep not needed...Renamed to DLClist.bac...game loaded.
Only other .txt file I saw was....Credit.txt. also renamed and the Game loaded....

You must have nuked a ESP that was still being used by the game.....reinstall time?

You may want to consider using an installation tool like OBMM or Wrye Bash's installer BAIN, if you do make a mistake when changing items in your Oblivion\Data folder, Reinstalling missing and corrupted esp files is easy to do.
Wrye Bash and BAIN are difficult to use at first, but they are superior to OBMM when you are running lots of mods together.
If you are not running a lot of mods, OBMM can help in situations like this also.
I did not realise this morning you had erased all of your esp files accidentally.

Na he said..." I've erased not used esp files, TES4edit backups and text files from Data folder. This text file erasing I blame for my problem.

As the OP asked for an easy way to fix this...yes..IF using Wrye Bash you could just look at your save ..on the "save tab" and see just what mods it requires to load.

As camaro said above, that would be one way to locate the esp files you need for the save to load.

That said, if you really want to get into any serious mod usage and painless troubleshooting, you should learn Wrye Bash's BAIN installer feature. Drop the manual install - just too cumbersome and reinstalling mods is a PAIN without BAIN.