I am suffering from carpal tunnel syndrome, can taking methathione, which is known to cure arthritis help?

First - there is no "cure" for arthritis

Second - Metathione (glutathione) is a tripeptide (mixture of 3 amino acids) that is used as an over-the-counter antioxidant/detoxicant. I doubt that it would have much anti-inflammatory/anti-arthritis effect at all.

Your best bet for CTS is:
1) Measures such as proper wrist supports on your keyboard/mouse, minimizing repetitive motions (like those in sewing, knitting, typing, etc.)
2) Wearing a wrist brace at night
3) Plain ol' NSAIDs (Motrin, Naprosyn, etc.) to decrease the inflammation

If the above don't have an effect, and your symptoms are severe, a carpal tunnel release (surgery) may be your only option.

The above is for information purposes only and is not intended as medical advice. You should always contact your personal physician with any questions or concerns.