Unfortunately, I've never found a way to fix them. I've tried to dis-assemble some of them before for people but most are sealed units. I can change the plug in and that's about it. Sorry, but you're going to have to purchase a new one. They just don't make the chargers or the batteries very good anymore. Check your plug and plug in first as that is one problem I've dealt with.
My laptop charger isn't working. It's plugged in, switched on, and it just isn't charging. It's not even registering that the charger is plugged in. It sometimes works for a few minutes but then stops again. How can I fix it?
It sounds like the port for the charger could be damaged on your computer. You may need a new charger. Maybe it's not meeting contact long enough to obtain a charge for your laptop. If you have a old computer than you may need a new one - really hard to say.
The same happens with me but with my phone...what I discovered was that the switch it was plugging it in isn't proper....The inside isn't good. Might be the same problem for you...check it!