Engine running ok... bike not moving.... gears on....

Loosen the handle bar adjustment a lot, .then take a little slack out of the cable at the engine connection, then re-adjust the handlebar lever with a bout 1/8" play

Clutch probably not engaging. Could be a clutch mechanism problem.

driveshaft or chain

Have you tried pushing the bike, in neutrol with the engine running, and put it into gear whilst moving, from your thread i cant work out if it is a clutch problem or not, if it is, with the engine turned off, put the bike into gear, pull in the clutch and push the bike the bike will not move because of the cluutch drag, if the clutch is working, it will be slightly difficult to move but it will move without the engine turning over but , other things to consider the wires are connected on the clutch safety switch on the handlebar micro switch ajacent to the clutch lever, also the side stand safety switch, check that the plunger on the switch is not sticking due to hardened grease, dirt rust, etc

Hi could be your engine has partially seized through being standing for so long just put it in gear and bump it over a few times to turn the engine over and get things moveing again if this doesnt work check your starter and solenoid switch connections are ok good luck

Sounds like the clutch is worn out. It sounds like it is slipping so badly it won't transmit enough power to move the bike.
As far as only going in 3 gears with the engine not running, are you spinning the rear wheel while trying to shift it? The trans shafts have to be spinning to be able to shift through the entire gear range.Try shifting it with the engine running and see if you get all 5. If you do, there is no problem with the transmission.