I had a similar injury and had brain contusion (temporal and frontal lobes) happened 1 year 8 months ago and had lot of constant symptoms still (dizziness, head aches, fatigue etc.,) plus distorted sense of smell and taste. Mine is bizarre lately since it keeps changing through out the day and gets some what better in the night (meaning I can slightly have normal smell and taste). In the beginning it was so worse.
So there may be a chance you can get it back and is interesting you mentioned you got it back for a day or two. Did they give you any prednisone? Nothing much you can do but there are only few doctors I came across who can look into this but they are expensive (in U.S).
http://www.tasteandsmell.com/
You can also check the following link and few people reported they got it back.
http://www.medhelp.org/posts/Head--Traumatic-Brain-Injury/Head-trauma-causes-loss-of-smell-taste/show/612120