sounds a little odd.
which internet connection are you talking about?
personal .... or professional
and who provides it?
there are two methods of obtaining an ip address
manual -
Manually allocated addresses are registered to a user ... so you need to go to your admin - the admin needs to allocate a new address .... or find out who is using the existing.
auto using DHCP
(this is the most usual way of working) the network connection is configured to "ask" the server for an address everytime you switch on
(its just a tick in a box in the network settings - obtain an IP address automatically)
Sometimes the connection locks on .....
open a command prompt
run | cmd
then type
ipconfig /release
ipconfig /renew
or use the repair option in network connections