So I uninstalled my WhatsApp application but I didn't restore my old data because of a connection problem when I reinstalled it so I uninstalled it again and now the backup is not the old backup that I want. what can i do to restore the old backup?
I think if your WhatsApp backup on GoogleDrive is not what you want, you can't do anything about this online Backup.
If you have a backup of your sd-card / your previous WhatsApp files you can replace the new WhatsApp files with this backup.
Maybe this helps: https://www.whatsapp.com/faq/en/android/20887921