Need help asap 2000 chevy cavelier

i have a 2000 chevy cavelier started fine until yesterday when i turned it off it sounded like it just kept spinning i had to disconnect the battery to stop it then when i reconnected it it started cranking so i disconnected the connections to the starter and it then stoped now when i turn the key it makes a wierd sound kind of like a vacuum cleaner running never heard it before ive tried disconnecting the battery and connections to the starter nothing any advice?

Sounds like a bad starter or starter relay. Something is stuck causing the starter to always be engaged. The vacuum cleaner sound may be the starter spinning but not engaging the fly wheel. Can you whack the starter with a rubber mallet to see if that clears it up? If it does, get a new starter.

SteveCBT gave you some good advice, but I want to add another possibility, namely the ignition switch.
The GM recall for defective ignition switches is because of unintended engine shutdown while driving, but it isn’t inconceivable for a badly-designed switch to have the opposite effect also, thus causing the starter to run when it shouldn’t.

+1 for @SteveCBT. Also whack the starter solenoid itself (not too hard). Hopefully there hasn’t been any damage to the flexplate (flywheel) teeth

Another thought. Cavaliers around these years had a recall to install an extra relay to switch the starter on. This was to take the load off the wires to the ignition switch that ran through the steering column. With extended cranking these wires would overheat and melt causing them to short, sometimes even starting a fire. I had this recall myself on a 2000 Cavalier I had.

The starter usually has two connections to it, one thick wire which comes directly from the battery positive, and one thin wire that is 12 volts only when the key is in “start”, and comes from from the ignition switch, often via other circuitry.

The starter motor should only spin when both are above 10.5 volts. If the starter is spinning with the thin wire at zero volts, that would usually mean the starter solenoid contacts have welded themselves together, and the solution to that – assuming this car is like most cars these days, with the solenoid being part of the starter assembly – is to replace the starter motor.

Be careful in the meantime, as this situation can cause the car to start on fire. Best idea is to completely disconnect the battery and keep the car parked away from the house or any other structure until the problem is resolved. I had a friend who’s car caught on fire and burned up on the street due to this same problem.