lights at top of the stairs
There are several possibilities. When troubleshooting, you want to do the easiest checks first.
1. First check the light bulbs one at a time in a lamp outlet you know works. # bulbs out at once does not make sense but it can happen. If one of the bulbs is ok, then your problem could be in the fixture or more likely a switch.
2. Is anything else not working? You could have a tripped breaker. Check the breaker panel for a tripped breaker. Remember that tripped breakers do not necessarily move to the off position. They usually sit "almost on" and have to be pushed to the "off" position before you turn it on again.
3. Stair and hall lights are often controlled by 3-way switches. If someone wired up one of the switches wrong, you can get one switch working ok only if the other is in the right position. Sometimes in a new to you house, it can take time to figure out which switches control what.
Let us know if the above works. If not there may be some other things you can do before you call in an expert. Obviously what is safe for you to do will depend on your expertise.
Good luck Andy