If you r lesn has fallen and as a result is stuck, I have found on YT a totrial that can help. It has worked for me and saved me quite an expensive repair. I ahve copied teh title and link to the video below, good luck:
HOW TO Repair A DSLR Camera Lens That Is Crooked And Jammed After Being Dropped #DIY #Repair
https://www.youtube.com/watch?v=_4K1Ge5COW8&list=PLPz-I0BhXRDI1l8fTZTKJS-ymHxwp06hu