Hello Omir,
Sorry to hear your having probelms charging. Before attempting to make any major repairs, try using a different micro-usb charging cable. If you don't have a supplementary one, you can find one online or at your nearest computer store.
If this does not solve your issue, try to replace the charging port. This is going to require you to open the device. Please see the guide to replacing the charging port, above. If there is not one, here is the same repair for a similar device: [guide|12849]
If you have done this and the problem is still not resolved, try to replace the battery. This is also going to require you to open the device. Please see the guide to replacing the battery, above. If there is not one, here is the same repair for a similar device: [guide|7741]
I hope this helps, good luck!