Unfortanetly you can't restore deleted system files. You can only delet files that you created. I expect that you may be experiencing problems with your computer because system files control how the computer works. For the infected system file I would get the newest version of Norton Antivirus because it automatically will delet any viruses and will restore the infected file or folder. Actually I may have or may not have found a solution to your deletion problem. Get Norton System works which keeps a history of your deletions so you can restore anything that you have deleted on your computer. If neither of these work then you should get a new computer. Don't get angry if you had to pay a large amount of money because when you get a new computer the Norton software won't let you down.
no
viruses
All viruses can be deleted with the help of a good anti virus software and some time you need to run an anti spyware software too.
No
Viruses aren't really sent to the Recycle Bin; the files infected with viruses are sent there. So, even if an infected file is permanently deleted, it does not mean your computer is safe. Further, many sophisticated virus writers can make their malicious code resistant to deletion and can even propagate when the user tries to delete them. It's important to use a good anti-virus program -- there are more than several out there, including the free program, AVG -- almost all of which create a quarantine and provide safe, thorough removal.
Oncolytic viruses are viruses used in cancer treatment. They kill these viruses through chemical means in multiple stages by attacking infected cells.
PC viruses are usually 'contracted' from the internet - or by inserting an 'infected' disk into the computer's drive.
9 infected:10 computers
White blood cells
Prokaryotes can be infected by viruses.
Antibiotics do not work on viruses because viruses are not cells which can take in and out or be infected by specific processes.
Vaccines don't kill viruses or diseases; they prevent disease before you are infected.