Since you didn't mention if this is a one-time happening, it may go without saying, but I will anyway. Do you still have electricity going to your outlet? Could a fuse have blown?

I can address only problems that have arisen with my magnetic PondMaster pump. One time debris was been sucked in when the hose from the pre filter came loose. I removed the offending plant and the pump worked fine. Another time I discovered that the housing that held the impeller in place was cracked. I replaced the housing and the pump worked fine.

Do you have a pre-filter? If so, it is possible that is plugged with gunk and water can't pass through.

The final comment is that it could be that the pump just has worn out. I don't think the magnetic kind do, but others might.

I hope this helps. If not, perhaps someone else can chime in with suggestions. Good Luck.

We've an outlet in the house with a little button that must be reset whenever outside power quits. Called GFIsomething, I think.

I have a pump that won't restart after being turned off or if the power goes off and if I thump it on the side of the pond it starts up. It is a mag drive and just has this quirk.