How do i renew an IP address in computer ?...somehow lost mine in notebook?

have a network here....desktop & wireless notebook....been running fine for 3 years (same router,modem,etc.) no changes to system at all.got disconnected on pokerstars, tried to log back on in wireless notebook (says i need to renew my ip address) clicked windows repair..failed to renew it...how can i manually renew my IP addy ? desktop works fine.