Backing up your Gmail Contacts
Regularly backing up your contacts is a good idea, especially if you synchronize them with a program or extension like gContactSync just in case your or the program makes a mistake.
Open and login to Gmail, if necessary and click on the
Contacts link (or click
Near the top right, click the Export button.
Choose Everyone (My Contacts + Suggested Contacts) and
Choose to Save the file and pick an appropriate location
If you ever need to restore the backed up contacts, click on the Import button in Step 2 and follow the prompts.