hi, when i ride my toyota camry 2002 2.0 vvti the light of check engine and check oil starts flashing and the engine roaring seems like a tractor

Sounds a bit serious. A flashing light indicates a more serious problem than a steady 'on' light has been detected by the OBDII system, Maybe oil pump, or an obstruction in the oil pickup, ot over the life of the car you have been using junk $4 oil filters. Cheap oil filters cause problems. Hopefully this is not the case, it sounds like an accusation but I assure you I'm on your side. But bottom line: get it to a shop post haste. You can still save your engine, but oil light=oil pressure problems, OR possibly even low oil-- your car has that feature, the 2002 Camry 2.0L the light will come on with low oil quantity. Now, this sound..roaring...? Ya got me there, especially if it goes away after an oil change. That's an odd one.

thanks for your help, but i forgot to tell you that the oxygen sensor was wrecked and i asked my mechanic if i can use the car he said that i can,

Sure, you can drive the car, but not indefinitely, it needs to be repaired and meantime your gas mileage will suffer, and possibly cause other problems. The ECU doesn't 'know' what signal to send for proper fuel/air mix ratio without the 02 sensor. It has two, one upstream in exhaust manifold and another downstream just past cat. (click image for full screen)

And now that you mention it was 'wrecked' that choice of words could mean an exhaust leak for that 'roaring' ..but I fail to see what that has to do with an oil change

sorry i mean wasn't working because when i did diagnosis, there was written oxigen sensor failure

I need help locating my O2 sensors