Only the first one is correct. Also "You are asking something to buy, but there seems to be a problem." is incorrect. It would be better to say: "You are asking to buy something but there seems to be (or "there is") a problem." Note: No comma before the word "but" I commend you for your attempt! Please do not be discouraged if you make mistakes, your overall meaning was still understood. :)

If you are "asking to buy", you are the customer/buyer. However, your sentences are from the point of view of someone who is selling, not from someone who is "asking to buy". The store clerk would say: This is all we have. We don't have anymore. We don't have anything else. There is nothing else.

second one is wrong i guess

second one is not regular i guess