Disco 2 gear box problem

Stopped at the traffic lights and could'nt get into first gear, tried second gear no luck got it into third and stalled it, i started it up again and managed to get it into first. When i got to my destination i tried to reverse into a parking bay but it would'nt go into reverse i tried first gear and it would'nt go in so turned the engine off then back on and it went in no problem. I sat there with the engine off and just went through the gears, no problems, i drove back home and everything seemed ok until i had to reverse up the drive and again it would'nt go into reverse so turned the engine off and back on then it was ok again. Any idea's. Thanks

Presume it's a manual?
Will it go into gear when you switch the engine off?
What then happens if you subsequently start up again? Does it start moving?

Before starting to look into gearbox issues, check that all of these are OK - gearbox oil, clutch and gear lever bias.

Yes, turn engine off and it goes into gear and drive off like nothings happened. Changed the gear box oil last year to mtf 94 as recommended on here as i had been having difficulties getting in first gear which has improved a lot. Just been out for a short run and it seem's fine now, puzzled.

Thanks for the reply's. Been driving around the last couple of day's and everything seem's fine, i'll leave it till after Christmas now and see what happen's then take it the garage. Once again thank's for the reply's.