If you knew it had no prop shaft - then you can't really return it because its not there.
As MHM says - you need to let your insurance co know its been converted to 2WD as it may alter your premiums or they may not insure it.
Freelander does not have a "transfer box" as you would have in most 4x4 trucks. Its design is essentially a front wheel drive setup, but the front diff also has a PTO drive to the rear axle. This diff/PTO combo is called the IRD. To stop wind up the prop shaft to the back axle is split into 2 pieces and there is a VCU in the middle that allows the 2 axles to turn with small differences (eg for cornering) but when there are larger differences (eg the car loses traction) it will 'lock up' to ensure both axles are turning.
Sometimes people are lucky and the props were only removed because the bearings supporting the VCU were shot - in which case replacement props, VCU and bearings will restore the transmission.
More likely though is that there has been some form of 'wind up' in the transmission. This can be caused by not running 4 identical make/model or tyres or the VCU getting overly stiff. If the issue was noticed early enough and the props removed - then the IRD and rear diff may not have been damaged - but often they are.
You can check the IRD's condition by changing its oil - if it comes out greyish - that is the ground down bearings immersed in the oil and the IRD is gone. The oil of course may have been changed after any damage was done - so even if it looks OK that's no guarantee. You should feel for any lateral play in the pinion driving the prop shaft - there should be none. When the oil is out, you should also remove the pinion and check the condition of the teeth on the gear that is on the end of it and the gear it mates to. You should also check that there is no play where the drivers side drive shaft slots into the IRD - its support bearing is also another high wear area, although you would probably feel vibration if this was an issue.
These should give you an idea of the IRD's condition. If you need a reconditioned IRD they are about £700 from a reputable supplier. If the pinion/crown gears are not broken or worn, then you can buy bearing/cooler/seal kits for about £150 if you want to recondition it yourself (the gears are expensive so a recon unit makes sense if they're gone).
If you get props and VCU from a breakers - the VCU will probably be shot (to tight). You should test it and expect to need a reconditioned unit and new support bearings - about £270.
Labour charges are on top of this.
https://www.landyzone.co.uk/land-rover/tests-new-freelander-owners-should-do-on-their-car.312863/
Reputable supplier of parts...
http://www.bellengineering.co.uk/freelander-1-products/
Freelander is generally a pretty reliable car - it is this area of the transmission that has to be monitored and can cause big issues if not. The XEDI L Series diesels are probably the most reliable, I love mine and it has given me very little grief in my 7 years of ownership.