Q: Lost Most Contacts

If you think you lost them then it's simple, restore from your Time Machine backup. Also ensure in your iCloud settings that the setting are correct.

Please sign in to icloud.com and launch the Contacts web app. Are all your contacts there?

Reverse a restore

To go back to the calendars, reminders, or contacts that you had before restoring:

1. Sign in to iCloud.com
2. Click Settings.
3. Scroll down and click Restore Calendars and Reminders or Restore Contacts under Advanced.
4. Click Restore next to the date that you restored.
5. Click Restore again to confirm. After the restore completes, you'll get a notification on iCloud .com and an email to the address on file with your Apple ID.
6. An apple article is there : If you accidentally deleted your calendars, reminders, or contacts from iCloud - Apple Support

1. Please export your contacts directly from icloud.com to a file for safekeeping.

2. Back up all data.

3. Open the iCloud pane in System Preferences. Verify that you're signed in with your usual Apple ID. Uncheck the box marked Contacts. When prompted to confirm, select

          Delete From Mac

The contacts will still be on iCloud and on any other devices that sync with the same account. Leave the preference pane open.

4. Launch the Contacts application and verify that your iCloud contacts have been removed. If you keep all your contacts on iCloud, the database should now be empty.

5. In the iCloud preference pane, re-check the Contacts box and close the window. The contacts should reappear within a few seconds, if you're connected to the Internet. Otherwise, stop here and post your results.