If compressed air doesn't help, I would just buy a new one.
Keyboards are inexpensive just buy a new one. Sometimes stuff like food gets stuck on the keys just take it out, clean and pit it back. Do you tube to see an example just type clean pc keyboard
Sometimes can fix. Usually just buy another low cost one unless you have some special needs or need for gaming
Use another key
They try to sell you a new one!
That depends on what you mean by it's not working. Are you pushing down on the keyboard and it's not going all the way down. There might be some type of object or food underneath the keyboard. Maybe you installed an improper driver. If not then perhaps a new keyboard would be the best choice
Pop the key cover off. Check and clean the key. Put key cover back on. Try it.
You buy another one.
That sounds like sound advice
Try using some compressed air, if not probably need a new one
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