soft top won't close

Your convertible top mechanism is the hydraulic type, meaning on each side there are two cylinders filled with (usually) transmission fluid which, when pressure is applied, raise and lower the top. If one is leaking it sounds as though you either have a blown seal in one, or at the very least a low fluid condition causing the top not to raise or lower. Try removing the trunk lining panels near the fenders and adding fluid to the leaking cylinder to see if you can get the top to go up temporarily, but you will need to see a dealer or mechanic for more in-depth repairs.

what if your top is in the trunk and i can't get to the side panels

When the soft top won’t come up, will the hardtop on my 1996 320sl Mb be able to lock in place?