I want to retrieve deleted messages that i accidentally removed

Unfortunately, once a text is deleted from the device it isn't able to be retrieved. Now if it's a different kind of message you may have some options. The only way to get that text back would be to have it resent.

I assume your HTC phone is running Google Android. And here is a guide about how to recover Android device data, it will help you retrieve the contacts and data. How to recover lost deleted Android Data

Unless your voicemail system has a "wastebasket" feature, you cannot retrieve an accidentally deleted message. It's gone. Not many VM systems have this feature. Cisco does, but Mitel low-end (embedded) models do not. The high-end Mitel NuPoint systems do. Older Avaya/Octel systems also do not. Contact your Voice Mail System Manager to find out what features your system has and how to access them. I've been away from this product for several years so features may also have changed. Hope this helps.

if you have sync set up on your computer with Kies air they should be in there. If you don't they are gone.

Look for the manual of your AT&T 1725 digital answering machine

'deleted' means just that...can't be done

sorry, its gone :(