Most of the time, this is because you installed or used multiple versions of Chrome on you PC, resulting in the profile is overwritten. The solution is easy:
- Search or find folder "X:\Users\YOURUSERNAME\AppData\Local\Google\Chrome\User Data\Default"
- Delete the file with name "Web Data". That's all.
For Linux (take Ubuntu for example):
- cd into the "~/.config/google-chrome/Default/" directory (~ means your own home folder)
- delete the file "Web Data". All done.