Oil light staying on

When I turn the key to on, most of the warning and caution lights come on. When I start the engine, they go out fairly soon. The oil light stays on. If I turn the engine off and restart it, the light goes out, and does not come back on. This began very soon after an oil change. The oil is a little above the full line. During the oil change the mechanic had to work very hard to get either the oil filter or the drain plug out. Any thoughts?