I have hp laptop and I got problem in wireless

Hi there’
I have a hp laptop and it was connected to a wireless router,suddenly I got disconnected middle of doing my work on it.I have no idea what happened to wireless.Its almost more than a week I can’t able to connect my laptop to wireless.I took my laptop to a computer repair guy.He said it might be problem with ip adress, because on his shop my laptop wireless was working okay.I rebooted my laptop almost for 5 times.It has window xp.Still can’t able to get online from my laptop.Anybody has any idea whats wrong with my laptop.Why i can’t get online. Thanks