The effects of hacking are not always obvious, but you can monitor your computer's settings and bandwidth use if you suspect your computer has been compromised. Hackers sometimes leave traces they hope you will not see. By searching your settings and accounts, you can secure your computer and online profiles before a hacker can cause too much damage.
Unknown User Accounts
Check your computer's list of user accounts to make sure there are no unknown or suspicious accounts. There are two ways to do this: either via the "User Accounts" section of the Control Panel or by using Command Prompt. From your home screen, type "cmd," then press "Enter" to open Command Prompt. Type "net user" at the prompt, then press "Enter" again. A list of every user account on your computer, including Administrator and Guest, are displayed. If you see any account you did not add or do not recognize, delete it by typing "net user accountname /del" where "accountname" is replaced by the account you want to delete.
Applications Installed or Uninstalled
Hackers can install programs on your computer that give them access to your data. This malware often disguises itself as legitimate program so it can work undetected. View your list of installed programs from the Control Panel and look for any software you don't recognize. Sort the list by date if you think any software was installed recently. Before uninstalling anything, double check whether a program is a legitimate by performing a Web search; some new applications may be the result of a software update. Also make sure that all the programs you have installed are still there. Hackers may try to delete or disable your security software so their own malware is not detected. If you're worried that a hacker's program may be running currently, open Task Manager by pressing "Ctrl," "Alt" and "Del," then clicking the "Processes" tab.
Settings and Account Usage
If someone hacks your computer or if malware is installed, you may notice changes to your computer's settings. Your browser's home page may change, you may see some extra toolbars, new icons on your desktop or even a change to your online profiles. While this is not a guarantee that your computer or account has been compromised -- it could simply be annoying adware -- you should immediately scan your computer for malware, then change all of your passwords. Check all of your accounts and statements for variations in use or unfamiliar activity. For example, check recent bank statements for purchases you don't recognize or a sudden loss of money. Some hackers may try to be subtle so they can use your account in the long term while others may simply cause plenty of damage before moving on to another victim.
Extra Bandwidth Use
If your bandwidth use has suddenly spiked, it may be a sign that there is new software installed on your computer that is using your Internet connection. This can sometimes be caused by data-stealing software that then sends your personal information to the software's creator. The increase in bandwidth use may not be measurable by looking at your monthly use overall, so use a bandwidth monitoring utility like NetWorx, NetLimiter or FreeMeter to see specific details by the day, week and month (links in Resources).
Losing Account Access
If you're unable to log in to your online accounts, your passwords may have been changed. This is especially easy for hackers to accomplish if they gain access to your email account, which they can use to request new passwords for your other accounts. Attempt to recover your accounts yourself -- a hacker may not have been able to lock you out if he got into your accounts recently -- or contact your accounts' support to lock your accounts before much damage can be done. If your social media, email and instant messaging accounts have been compromised, tell your friends not to click any links or accept any file attachments until you have regained control of your accounts. The hacker can use your friends lists and address books to send malware to your friends and infect their devices as well.