It's almost always a good idea to put a UV filter on the front of your lens. The filter helps you get better, more saturated colors in your images while also protecting the precision glass on the front objective of your lens.
However, in the carrying out of that second duty -- protecting the front of your lens -- the filter can get stuck in place. If a hard knock to your lens damages or shatters the filter, there's a good chance that the lens itself is undamaged. But, if you can't easily unscrew the damaged filter, further inexpert attempts to remove it can damage an otherwise undamaged lens.
We are filter removal experts. Bring us your stuck or damaged filter and let us safely remove it.