Computer passwords have changed
Online passwords Sometimes, after an online account is hacked the attacker changes the password to one or more of accounts. Try using the forgot password feature to reset the password. If your e-mail address has changed or this feature does not work, contact the company who is providing the service. they are the only ones who can reset your account.
Local computer password: If your password to log into your computer has changed, it may have been hacked. There is no reason why a password would change on its own.
E-mail spam being sent
When an e-mail account is taken over, the attacker almost always uses that account to spread spam and viruses. If your friends, family, or coworkers are receiving advertising e-mail from you, your e-mail is compromised. Log into your e-mail and change your e-mail account password.
Tip: E-mail addresses can also be spoofed without hacking the account. After changing the e-mail password, if your friends continue to get e-mails you have not sent, it is likely someone is spoofing your e-mail address.
Increased network activity
For any attacker to take control of a computer, they must remotely connect to it. When someone is remotely connected to your computer, your Internet connection will be slower. Also, many times after the computer is hacked it becomes a zombie to attack other computers. Installing a band width monitor program on the computer can help determine what programs are using what band width on your computer. Windows users can also use the netstat command to determine remote established network connections and open ports.