whatsapp installation I created a group on whatthap and lost contact to get to the platform for months, I got another phone and restored my whatshapp account, only to discover that I couldn't recover the group created by me. Pls what do I do?
I got this thread from Quora : 

If the owner of a group deletes the group, then WhatsApp randomly assigns the ownership of the group to a group member. Unfortunately, there is no option to get back the ownership of the group right now unless the current group owner adds you to the group and transfer the ownership of the group. You can ask some other friend who is still the part of group to see for its admin, and then you can ask admin to add you.

WhatsApp automatically backs up your chats every night.
You can initiate a restoration by simply uninstalling and reinstalling WhatsApp.
Click Restore when prompted to restore your chats.
Your chats should appear in WhatsApp!
Details

WhatsApp automatically makes backups every day at 3 AM and stores them in the WhatsApp folder of your Android phone. This folder is either located in your device's internal memory or external SD card. Depending on your settings, WhatsApp could also make a backup to Google Drive. To restore the most recent backup, you will need to uninstall and reinstall WhatsApp.

If you need to restore older messages, check out "Restoring older (less recent) backups".

During the installation process, you will be prompted to restore your message history. Choose Restore to recover your chats.

Also recommend:

Make sure you have a file manager. This will be useful for renaming the backup files.

If you do not want to lose your current history (newest messages), create a manual backup by going to:
WhatsApp > Menu Button > Settings > Chats and calls > Back up chats or Chat backup.

This manual backup file will be saved as msgstore.db.crypt8 in your /sdcard/WhatsApp/Databases folder. Save this file as msgstore.db.crypt8.current so you do not get it confused with other backup files during the restoration process.

Note: Your backup files are saved in the /sdcard/WhatsApp/Databases folder. This folder may be located in either your device's internal memory or external memory.

Hope that helps !! 

You can also use Android Recovery App to get back your whatsapp Folder if was deleted. 

Check this Link : https://www.quora.com/WhatsApp-7/How-do-I-find-a-WhatsApp-group-I-deleted-by-mistake