I have a bmw 2001 325ci I could not turn the steering wheel at all this morning please help

turn steering wheel hard back and forth while trying to turn key sounds like the steering lock tab causing problem

sounds like the key may be worn out..check the appearance of it if it is worn a little smooth that could cause the problem you're describing.

check for loose steering rack /box check all ball joint ends . check that the suspension units are not loose when turning the wheel

Look inside the reservoir while the car is running and see if it is low. If it is turn the car off and add power steering fluid. You can purchase at a gas station or parts house. Some people use transmission fluid but it is not a good Idea because it can cetch on fire if you have leak in your power steering system. You can look for leaks when you have someone steer the car fom side to side. Make sure you turn the wheel tight so the whinng is at it's loudest. Check your power steering hoses and rack and pinion,etc. Hope this helps leave a comment.

Sorry I have not done a BMW but steering wheels usually require a puller to remove from the spline.
I have mostly worked on *** cars and the steering lock and key are removed without the steering wheel removed. The lock assembly attaches around the steering column, and is held on by some tamperproof bolts which break the hex off on installation, so you are left with round heads that look like rivets, I use a small chisel or punch to get them turning, it may be possible to drill the heads off as well, Sorry again if my info only relates to japanese cars, but hopfully I helped with the steering wheel removal.

I also 2001 bmw 325ci. Your description of events exactly matches mine, right down to the problem occurring immediately after a sudden turn. Turns out it was the steering pump. I'm not a mechanic but have fiddled around with stuff over the years. I used the following link to replace mine. Saved several hundred dollars. GOOD LUCK! http://forum.e46fanatics.com/showthread.php?t=575499&highlight=luk+lf+20

Your powered steering pump needs checking out as it sounds like a reco pump is needed and the rest of the steering needs a good check over ,but yes do check your fluid as if its low or empty then it can cost you more
It should be checked like the rest of the car every 3000 km same as Battery/Engine oil/Brake fluid/Tyres/ etc ...

Read the owners manual on resetting your door control seat preference this will include steering column and pedal adjustment if installed on your 7.

Replace the power steering pump should fix it. Have seen both failed pump and steering racks cause this problem.

Your steering wheel may be jammed. This happens when you park on an incline and the force of the car rolling back jams the steering. Try to turn the steering wheel hard in one direction while trying to crank, then the other direction if the first doesn't work. You may need to take pressure off of the steering lock by pushing the car a little bit.