i let someone hook their laptop up to my cable connection and use it now my pc won't connect to the internet a

Was it connected to a router or directly to the modem? Either way power cycle the units, modem or router, to release the MAC address from the APR table. The unit may not be able to issue another IP address till this is cleared. See if that helps.

what is your internet set-up? ethernet or wireless?

for ethernet / USB cable connection > go to control panel > open network connections > if LAN is disable/ not connected >right click and enable/ connect it

for wireless > control panel > network connections > right click on wireless connection and enable/ connect it

Check your settings

MENUE at the top

TOOLS

INTERNET OPTIONS

CONNECTIONS

Than Put a check in the box that applies to your connection

If your on DSL wireless put the check on Never dial a connection

etc etc etc..

land line connection should be DIAL MY DEFAULT CONNECTION

run 'cmd' . at the prompt type 'ipconfig /release' then at the next prompt type 'ipconfig /renew