A friend of mine was having trouble with his computer and he brought it over to my house for me to test for viruses and do a general update. What I found was that even though this was an older computer, with very little memory, it still booted quickly and ran great on my network. However when he took it home, he was still having trouble getting on the internet and kept saying that he thought he needed to buy a new computer.
My solution is to reboot his modem/router by uplugging them from their electrical source and then waiting 15 seconds. Plug them back in and wait a few minutes for them to do a reboot and make a connection to the internet. Your computer is usually fine at this point. If it’s not then turn off your computer and then restart it again. this will solve 99.9% of most problems.
Note – you may have two devices – a router and a cable/modem or they may be integrated into one box. If you don’t have a router – buy one today as it acts as a firewall to the outside world.