1 If you are not familiar with the phone and that is stopping you from checking (in fear you might delete something) then go into a phone shop and ask to see one, explaining you are worried you won’t understand how to work the text messages.
2 If you want to read some messages which have not been opened yet, check whether or not you can tick them as "unread” after. You will need to know the phone make and model; then either ring a phone shop to check or run a Google search on it.
3 If you want to track and read her messages you could download mobile spy software like Mobile Spy (www.mobile-spy.com). You would have to actually download this on her phone and it then claims to allow you to track and read her text messages without actually having her phone. However, you must check privacy laws before doing this as you may be breaking the law.
As I said at the beginning of this post, you need to think about whether you really want to be checking your wife’s text messages without her knowing. It is an invasion of privacy and you should ask yourself how you would feel if she did this to you. Also, if you find any evidence that she is having an affair you may have to admit to reading her phone - and text messages can often be misinterpreted at the best of times.