Hello. My wife and I bought a house last year for $400K in California. At the time we were living with relatives in the same city. 2 months later due to personal reasons we had to sell the house. After taking into consideration improvements, commotions and other selling expenses we ended up losing money on the sale (about $15K). We NEVER lived in the house. Can we deduct the loss on our tax return?

No - the only way you can deduct the loss would be if this was an investment property. Since it was not, it is considered personal property and hence you can not deduct the loss.