How do I get out of my problem of not achieving results, feelings of worthlessness, guilt and rejection?
Should I change project?
  Should I change to dry lab?
  


A PhD can be extremely frustrating and discouraging.  Whatever you do, don't make a major decision while you are stressed and upset. Take a deep breath (and maybe a day off) and decide what you need to focus on.

Since you will be qualing soon, you likely need to spend a significant amount of time studying for that.  Passing your quals are important, and will likely give you a confidence boost.

Secondly, consider finding a social outlet.  Many grad departments have a weekly social meet-up at a bar.  Apart from meeting people that work in different labs, it is also quite likely you will meet other people who have gone through this issue, and will help you.