If your Android device is synced with your Google account, the odds of recovering missing contacts are definitively in your favor. Gmail has a nifty feature, that allows you to restore a backup of all your contacts, which can date up to 30 days back. Once you have done this, you can re-sync your device with your Google account and get all your contacts back.
Sidenote: if your contacts are appearing in Gmail but not on your phone, see the steps above and/or try re-syncing your Google accounts completely.
To restore a backup of your Gmail contacts, go to your inbox and select “Contacts” from the dropdown menu on your left hand side.
Once you see the list of your contacts (or not), click on “More” to get to the dropdown menu, where you need to select the option “Restore contacts…”.
Now you should see this pop-up window, where you can select a backup, which can date back as far as 30 days. If this method worked for you, go ahead and re-sync your Google account on your Android device and you should be good to go.