While part of a Roland electric piano may not be functioning properly, fairly often the problem is due to a simple issue that can be easily fixed by the user. The following information is drawn from the owner's manual for the Roland F-100 piano (available in the resources section).
If the piano simply won't turn on, first check the AC adapter and power cord. The AC adapter should be connected to an AC power cord, which plugs into the wall. The adapter itself should be connected to the DC connector on the rear of the piano. If the adapter is properly connected but the piano still won't turn on, there is a chance it is broken and needs replacing. Check the cord to see if you can find any torn wires, although they may not be visible. If a replacement is needed, replacement adapters are usually fairly inexpensive and can be purchased on a site such as Amazon or from the Roland company itself.
If the keyboard turns on but no sound is produced, first make sure the volume is turned up. If it is and sound is still not produced, check the headphone jack; if headphones or even an adapter for your headphones is left in the jack, no sound will be produced. Next, check that the speaker cable is properly connected. The speaker cable is located on the rear of the Roland piano's speaker and connects to the speaker connector on your piano.
If your Roland keyboard's buttons are not functioning, "panel lock" may be on. To turn panel lock off, turn the volume all the way down and turn off the keyboard. When you turn the power back on, panel lock should be off and your buttons should work.
If your issue is not one of the issues listed above, consult your Roland piano's manual (you can find this in the Resources section of this page). If you cannot resolve the issue on your own, you may need to consult Roland's repair service, either through the store where you purchased the keyboard or on their website at rolandus.com.
Always unplug your electric piano before attaching or examining wires and cords.