IR remotes are pretty simple devices so fixing it may be a possibilty.
Firstly, establish if any IR is being emitted by viewing the emitter through a digital camera/camera phone. The emitter will glow brightly through the camera when a button is pressed. If it doesn't there are three likely causes.
Assuming that the batteries are good, there could be some corrosion/dirt on the battery terminals or the connection to the PCB could have become "dry". This is essentially a crack in the solder joint resulting in no power. The joint can be simply remade with a little fresh solder & a soldering iron.
Similarly, one of the joints to the LED emitter itself may have become dry & the same fix applies.
Intermittent buttons or needing hard presses is likely to be dirty contacts on the keypad/ PCB. These can be cleaned with isopropyl alcohol but don't rub too hard as you can damage either surface.
The most difficult task is likely to be getting it apart in the first place! After removing any screws, an old credit card run between the two halves will usually pop the clips that hold it together. If you're going to bin it anyway you've got nothing to lose.