Water won't come back on after turning main back on
Is the main valve a gate valve?  If so, you'll probably have to replace it. These types of values often fail when not used for a long time, and either won't close or won't open again after being closed. 

You may be able to repair the valve, but you'll have to shut the water off to do that, so you might as well just replace it with a new valve.  If fact, you should replace it with a ball valve (aka quarter turn valve). Ball valves are more reliable, and typically don't break from not being used.