If the remote is not responding, check to make sure that nothing is obstructing the direct line of sight between the IR blaster of the remote and the IR receiver of the fan. If this does not help, use this guide to check the batteries of the remote. If the remote still isn't working, you will have to fix the remotes circuit board or the fan’s IR receiver.
If the fan isn't oscillating, check that both the remote and front panel are functional to eliminate the chance that the button is simply broken. If this does not help, remove the back casing from the fan. Then, locate any debris or objects that might have gotten into the fan and blocked the oscillation motor. If the fan is still not oscillating, replace the oscillation motor assembly using this guide.
If the front panel buttons are not responding, the buttons are likely stuck because dirt or other debris has gotten into them. Take the fan apart and clean, or possibly replace, the buttons using this guide.