Will lloyd

I have a landrover series 3 diesel 88” which was driven into the shed just before covid due to lack of use, all working ok. I have come to it this spring to start a light restoration to find issues with clutch. The gears can be selected with the engine running and no drive happens. Have changed the master cylinder and system has bled up ok with no leaks etc. bit stumped now as to what it could be and after a second opinion thanks in advance 👍