Orders are not appearing in the administration section

[rotoxtc]

Since I noticed there had been no orders in the last few days, I tried to make an order in my shop, and I found out that, while all the operation seems to go smoothly, at the end there is no trace of the order in the database (the shop address gets no e-mail, and there is no trace of the order in the customer's account), even if the quantities are correctly decreased, and the customer receives his confirmation e-mail. Does anybody know what could be happening? I have been attacked by hackers some weeks ago, maybe this is related.

Thanks.