You say the rotor doesn't turn when the ignition is on. I assume that you mean when the engine is cranking. There are several things which could cause this, all mechanical problems, not electrical.
If the rotor is not turning when cranked then either the camshaft is not turning or the drive on the distributor is not engaging the drive from the camshaft (or, least likely the distributor mainshaft is broken). The drive could be by a gear directly off of the camshaft, or by a cog type of engagement from a camshaft driven oil pump.
Pull the distributor (usually by removing one bolt holding a clamp at the base of the distributor and just pulling it out of the engine)and examine the bottom end of the distributor shaft. Is there a broken gear or drive pin? If so you will need to replace it and install it into the engine again to see if it turns, indicating there is no internal damage to the driving member. If the distributor, after replacing the drive gear, turns while the engine is cranked then you will need to re time it in relation with the camshaft in order to complete the repair (not really that hard, but you will need to pull a valve cover to see the position of the itake & exhaust valve on #1 cylinder in relation to the ignition timing mark on the crank pulley. Intake & exhaust valves need to be fully closed and timing mark at TDC indicating a fully compressed cylinder ready to fire). BTW,it is usually cheap to buy whole distributor from a salvage yard and easier than replacing the parts. It is a good idea to mark the plug wire positions if you have removed them from the cap or spark plugs before you remove the distributor.
If you pull the distributor and the drive end looks fine (no missing gear teeth or broken cogs, pins, etc.) You will need to pull a valve cover and crank the engine to see if the camshaft is turning. Just watch to see if valves are going up and down while cranking. If they don't move you have abroken timing chain (or maybe belt, I don't know for sure which your engine uses). Or, possibly, a broken camshift or cam driving gear. If you r engine uses a belt, it is fairly cheap to replace and see if the problem is cured (you should be able to look at the belt and see if it is broken after removing the appropriate cover). Be aware that a broken belt or chain, on some engines, will destroy the engine internally by pistons hitting the open valves. If you find a broken belt (or chain) ask a subaru dealer mechanic if this is the case with your particular engine, since you might not want to proceed with a repair attempt if it is.
If your engine uses a timing chain (as mine did) this is an internal engine repair. You should be a fairly experienced mechanic before attempting internal repairs, and have a fairly well stocked tool box, access to a garage or other convenient indoor area, and an engine pulling hoist. Again, ask an experienced Subaru mechanic to see if a broken chain has probably destroyed your particular engine or not when considering an internal repair.
If the timing chain is the problem (of a broken belt has caused probable major internal damage) you may want to consider a new engine rather than a repair. A rebuilt engine could run you 1200+ dollars, but that would be more than the car would merit, However, a bit of looking around at salvage yards and classified ads should find you a good used engine for around 150 to 175 dollars. Replacing an engine whole is a fairly simple bolt turning job. You can rent a lift at most rental stores ( or do like I did with my brat and just grab ahold and manhadle it in and out if your strong enough). A used engine usually has the accessories attached (distributor, carburetor, manifolds, etc) and is quick to get up and running. A one day job, or less with a helper. If you have a manual transmission, it's a good idea to replace the clutch disk while the engine is out if you ahve many miles since your last clutch replacement. Saves doing the whold process again in the future.