How old is your phone?
Really old? Use this: http://www.my-symbian.com/s80/software/applications.php?faq=17&fldAuto=275
SMS Journal is a small application for MS Windows. It consists of only one file and can be placed in any folder. SMS Journal lets you browse, read, edit and delete SMS messages on your PC and also export them to a text file, HTML etc.
Blackberry? Use this: https://appworld.blackberry.com/webstore/content/362 from the Blackberry App Wold. Cortado Basic Print allows you to instantly print photos and images saved on your BlackBerry to the nearest printer. Use Cortado Basic Print to easily print (over Bluetooth) your e-mails, appointments, contacts, tasks, and memos.
Andriod? Use this: http://wiki.brilaps.com/wikka.php?wakka=Txtract With TXTract SMS backups can be created as HTML,XML or CSV files. MMS media is copied over to the microSD card. Now that you have backup of your text messages, you can delete certain threads, or clear the entire Messaging storage to make your Messaging application run much faster. With Txtract, not only can you backup your SMS messages, but you can also send them to your email.
Windows phone? Bless you. Use this: http://www.dotfred.net/ The PIM backup application is a tool that allows to backup/restore personal information stored on windows mobile based pocket devices. Concerning the personal information, I refer to contacts, appointments, tasks, messages, calls,...
The backup is totally independent of the version of Windows Mobile running on the device and independent of the device itself.
If the text messages were delted from the phone you need a court order for verizon to retrieve them and they don't keep them very long on the servers I heard. Mary