Question ACER 5742 won't run on mains

[oldcelt]

The laptop will charge from mains adapter then run on battery power. However, it will not run on mains power.

Would appreciate any advice.

 

[webworkings]

A little clarification please. Are you saying when it is plugged in it won't run or charge, if you try to turn it on, and it charges when off. Then will run only when on the battery alone?