Viruses are quite different from bacteria.
Bacteria are living cells that can multiply on their own — a virus cannot. Instead, a virus gets into the cells of your body and uses them to make multiple copies of itself. The new viruses, which are exact copies of the original virus, break out of the cell, killing it. The new viruses then go on to infect nearby cells, starting the process all over again.
To stop a viral infection, a treatment must either help your body’s immune system to recognise and kill the viruses to prevent them from causing illness (e.g. vaccines), or it must stop the viruses that have got into your cells from multiplying so that the infection cannot spread and cause illness (e.g. antiviral treatments for flu and HIV infection).
Antibiotics cannot be used to treat infections caused by viruses, but they can be used to treat bacterial infections. Most viral infections do not have an antiviral treatment.
Some viruses (e.g. influenza [flu] viruses) can still cause infection if they have been on surfaces, such as door knobs or plastic toys, for a short time. That is why it is important to always use a handkerchief or tissue when you sneeze or cough, and to always wash your hands with soap and warm water before preparing food or eating.