How can i see deleted messages on instagram?

You cannot recover Instagram DMs that were deleted — Meta removes them for both participants and there is no restore, trash folder or export that brings back a thread that is already gone. What you can do is collect the traces that survive outside the chat, and understand the difference between "delete for you" and "unsend".

The traces that still exist:

1. Notification previews. Lock-screen and notification-centre previews on any device that was signed in can show the first lines of messages received before the deletion. Screenshot them early; they expire.
2. Email notifications. If Instagram email notifications were ever enabled, the account's mailbox holds message previews going back months.
3. Download Your Information. Settings → Accounts Centre → Your information and permissions → Download your information, select Messages, request JSON. It returns what Meta still retains — usually the thread skeleton, not the deleted text.
4. A device backup taken before the deletion. An iCloud or local backup from an earlier date can restore locally cached copies of a thread when the app is reinstalled from that backup. It is inconsistent and depends on what was cached, but it is the only route that ever brings text back.

We covered the longer version in this thread.

Where monitoring tools stand, honestly: Ultimate Phone Spy covers Android 4.0+, Windows and Mac and cannot read Instagram DMs at all — no tool can, since Instagram messages are encrypted in transit and end-to-end where that is enabled. What the Android build does give a parent is SMS, call logs, location and installed-app activity (sms tracker). If the only thing you need is deleted Instagram text, no purchase will solve it, and you should not buy for that reason.

The legal line: reading another adult's messages without their consent is unlawful in most jurisdictions, and "recovering" them is not a loophole. For a minor in your care, the honest path is account-level transparency, not recovery software.