What cause pain in the wist?

Wrist pain. Wrist pain can be from a variety of reasons, but most likely is related to repetitive trauma from things like keyboards/computers and manual work. Other questions: any swelling, any finger swelling, any redness, any fever, any rash or other infections? Answers to these may alter the diagnosis.
Many. There are many causes of wrist pain: tendinitis, arthritis, sprains, fractures, and nerve entrapment syndromes. If symptoms are the result of an acute injury, you should be evaluated and treated. If symptoms are minor and started spontaneously without injury, try rest, ice, elevation and immodiliation (bracing). If your symptoms continue beyond a week or so, see your primary care doctor.