You can restore accidently deleted Gmail Contacts from Gmail.
You can undo any deletion or any merging or any activity by 30 days. you can customize the days and hours too as seen in the below image.
Click contacts on the left side. And on top of the contacts list click More Actions
You will find the below “Restore Contacts†option popping up
Choose the required time frame and click restore.
Once you Click Restore, you will find the result in yellow color on top with an undo option.
This way you can restore accidently deleted Gmail contacts very easily.