If you disconnect the opener from the door by pulling down on the little red handle, does the door function properly? Regardless of what might be wrong with the opener, it's important that the door move smoothly and is balanced.

If this is a Chamberlain/Lift Master/Craftsman (all made by the same company) chain drive opener there's a little plastic gear inside that's a common source of problems and causes what you're describing. It's about a $25-30 kit that comes with the gears, lube, miscellaneous hardware, and instructions that's available online and from garage door companies (not the big box stores). It's not horribly difficult to install and takes about an hour or a little more.

Thanks for your help my husband had a look at it and rang up a couple of places and they all said it was the motor so we went to bunnings and got a whole new motor so now it's the fun part trying to figure out the stupid instructions .Thanks again for your help

If it sounds like it's running, and stops after about the amount of time normally it takes the door to raise or lower, I'd be surprised if it wasn't just the neoprene gears as mike suggested.