2004,Loose gearbox that won’t find 2nd or 5th gear, sometimes hard to differentiate between 1st and 3rd.

The gears work fine and there seems to be no grinding of gears, the changes are all still smooth but it will not go into second gear at all, it is like the place for the gear lever to go into 2nd does not exist, the same applies for 5th, I try put it in gear and it just falls into neutral. All gears were fine the other day but now this has occurred. Also the gearbox seems very loose and there is a lot of give when in gear. It's very hard to distinguish which gear you are actually in. Any idea what this could be? I think it could be the gear linkage but haven't had time to get it looked