my ipad mini charger isn't working should i buy a new charger cause when i charge the ipad charger sometime works and then when i charge it then the charger doesn't work

Is your iPad less than a year old or still under an extended warranty? If so then I'd make an appointment at an apple store or authorized service provider and have them check it out. It could be covered under the warranty.

If your iPad isn't under warranty, I'd buy a new charger, but buy it from a place that takes returns. Use it and see if it works. If it does, keep it, if it doesn't then return it. (another thing could be to borrow a friend's charger). You may also want to try a different cable. See if that's the issue.

If your iPad won't charge with a new charger then make an appointment at an apple store or authorized service provider and have them check it out. They could offer you an out of warranty replacement. Or you shop for a new one. (personally I'd find it worth the drive for me to have them look at it, unless your iPad is one of the first gen ones, then you may be money ahead to simply cut your losses and start with a new iPad.