Some of this you can check yourself before calling anyone. If the opener runs but the door won't move, look at the photo-eye sensors near the floor on each side of the track - a knocked-out-of-alignment sensor is the single most common reason an opener refuses to close a door, and it's a five-minute fix with no tools. If the remote stops working but the wall button still fires the opener, try reprogramming before assuming the opener itself failed.
What we don't recommend taking on yourself: anything involving the logic board, the drive gear inside the unit's housing, or the high-tension spring that some older opener-and-door combinations still share a mounting point with. Those aren't jobs where a mistake costs you an afternoon - a spring under tension can cause a real injury, and a board wired wrong can take out the opener's motor along with it.
If you're not sure which category your problem falls into, that's a fair reason to call before you start pulling panels off the unit. We'd rather answer a question that turns out to be nothing than get called out after a DIY attempt that's made the fault harder to diagnose.