I deleted messages on iphone 12 last month and would like them back. my last back up was yesterday. can i get them backi get them back?

If iCloud Messages is enabled, no. With iCloud Messages enabled, deleted messages are permanently deleted.

If iCloud Messages is not enabled, and if you have a backup from prior to the deletion, and are willing to revert the entire device contents and all data to the backup prior to the deletion, probably.

Given you seemingly have no month-old backups available, no.

Your remaining option is to ask another party in the conversation for screen shots, if they still have those.

Delete a message or conversation

When you delete a message or conversation, you can't get it back. So make sure that you save important information from your messages.

Retrieving isn't as easy as you think it is...

Restoring from iTunes backup is an option but you need to restore the entire iPhone (only messages restoration option does not exist) including all apps, Photos, Videos, Voice Memos, Notes on your iPhone etc...

The question is when did you backup on iTunes and when did you delete it...Read on...

Let us assume...

Date1: Backup date

Date2: Message Deletion Date

Date3: Current Date / Restoration Date

Given that --> Date1 < Date2 < Date3 

1. Risk of restoring on Date3:
   1. You may lose data between the Date1 & Date 3
   2. By default, iTunes creates incremental backup over the existing backup such that you only will have one backup per device on iTunes
   3. If you have taken another backup between Date2 and Date3, then the messages that had been deleted on the device on Date 2 is also deleted on the backup.
   4. If point no. 3 is true the messages or lost completely.
2. Else you have a mitigation process: Create Multiple back-ups on iTunes for the same device.

How to create Multiple Backups for the same device.

1. On iTunes Click on Manage Backups
2. Right Click on a Backup and Click Archive
3. Click Backup Now.
4. You will see a fresh backup will get created See the GIF below

1. Restore from Backup dated Date1 (Archived)
2. Retrieve the message and store it separately
3. Restore from Current Backup Date3