Donna,
Was it a laptop or tower?
There is an icon at the top that connect to wifi, if you touch it, it can turn off. If that happens it starts searching for another signal which can be too far away. Like a neighbors unprotected or business nearby.

For virus protection there are many very good free ones. My work uses AVG, free version, my dd uses AVST free.

Hope it is resolved, but get the protection on, the viruses can really crash a computer making the hard drive fried.
Di