There are many android phone users, and losing important phone numbers from it happens unexpectedly. But if you need to recover them, you can use an android recvoery app to help.
Just google it, you'll find many answers, and I found these two guides are really helpful. And they're also easy to use, you just need a few simple steps to recover your android phone contacts to pc.
And you need to root your android phone at first, or the app can't detect your phone successfully. And stop saving new data to your phone, or the deleted data will be covered.
Recover Deleted Contacts from Android Phone
Recover Deleted Phone Numbers from Android Phone