There are no guaranteed ways to protect yourself from a virus or malware but the best practice is to keep your computer’s operating system updated and AntiVirus/malware software packages updated. Manually check for updates just in case the software is not updating properly.
All computers get sluggish over time from being used. If your computer becomes sluggish or starts doing things that are not normal you may have a virus or malware. It is well worth your time to check for updates on all of your programs including your virus protection and then do a complete scan and cleanup because many viruses start out as just annoying but if left unremoved can get much worse quickly.
There are many issues that will keep you from connecting to your wireless router. Here are some of the most common. If your device has been connected to the wireless router before but won’t connect now, try rebooting your router by unplugging the power to the router for about a minute. Then plug the router back in and give it a minute or two to get connected and give it atry again. If you have never been able to get connected to your wireless router with your device you are most likely using the wrong wireless password or a wireless network with the same name as previously setup on the device with a different password. Either way check the list of known wireless networks and remove the one that has the same name as your wireless router and try to connect again with the correct password.