Hi, I'm new to Oblivion and it's great. I have a problem though. The game is in French (I have no problem understanding it),
and I would rather have it in English science alot of the awsome mods are in english. I looked everywhere on the net and
I found nothing .I need help plz

You can use english mods too, it wouldn't make a difference as they are made the way they work with other versions of Oblivion too.
The only problem that you might experience then would be that shop and housenames appear in English, most conversations plus audiofiles will still be in french then. I have a German version of Oblivion, but my English is very good so I do not care. The mix is strange in the beginning but you'll get used to it. I'm far too lazy to translate every of my 250 mods I'm running.

So to your question. I don't know about a way to change the language other than to get an UK or US copy of Oblivion and re-install it. And if you have an option to install it in English re-install it too. Otherwise you can still use stuff of other languages and be fine.

Actually, there are more. If you use English version of any mod that changes vanilla race(s), you may get 'No voice'. And if any mod changes existing cell names to other language, your saves(all of them) may be deleted when you try to save your game there.

I don't know about savegames, never had that problem before although most of my game is in English now. I'm running a lot more than 100 mods and at least 100 of them are English and everything's renamed ingame but other than that thigs are fine.
You can easily change the no voice issue by either replacing the original names of your races in CS or loading a custom race fix mod at the very end of your modlist. Then even edited normal races will not experience the no voice issue.