Note app is showing “Folder” by default and no other option to work

Greetings, gauravsir183.

It appears that you're using iCloud to sync your notes across devices. The issue is, there aren't any notes in the Notes application on your iPhone 7 Plus. I'm happy to help.

iCloud: Delete a note -- Check iCloud.com for recently deleted notes.

Recover recently deleted notes

If you’re using upgraded notes, you can recover and edit iCloud notes you deleted in the last 30 days on iCloud.com or your devices where you’re signed in with the same Apple ID. However, you can’t recover notes you permanently removed (as described in Permanently remove recently deleted notes).

1. Select Recently Deleted on the left.
   If you don’t see Recently Deleted in the folder list on the left, you don’t have any recoverable notes.
   If you don’t see a folder list to the left of the notes list, you’re not using upgraded notes and can’t recover deleted notes.
2. Select a note on the left, then click Recover in the toolbar. The note moves to the Notes folder.
   To recover directly to a folder other than Notes, drag a note from the Recently Deleted folder to another folder.

Note: If you delete a shared note that you do not own, the note does not move to your Recently Deleted folder. For more information, see Delete shared notes.

Take care!