I've done varicocele surgery before 2 days and now i feel pressure on neck and severe headache when i stand, and fine when i'm laying on bed.

Explanation : Your question should be first addressed to your surgeon, because he knows your general medical condition and what anesthesia was used for surgery. If it just local anesthesia, may be your headache not related to recent surgery at all and requires appointment with your primary doctor.

See below : If your surgery was done under a "spinal anesthesia," then your symptoms are most consistent with a "spinal headache." In such case, bedrest, increased oral fluids, caffeine, and pain meds can all be helpful. More severe or persistent cases are treated with a "blood patch" by an anesthesiologist. That said, regardless of the type of anesthesia you had, I would recommend you contact your surgeon.