sounds like your sim could be screwed, i've been through 2 since I've had the g1 and I had a similar problem. Since I already been through 2 sims I thought they were free, lol, but my friend just paid $80 for one so I guess not. How I've got my sims free, just call tmo's customer care, let them troubleshoot you, if that doesn't work, they'll tell u 2 go a branch to get a new sim, verify that's it's gonna be free and that's it.
Go to your Gmail account, scroll to the left, click on contacts........Aren't all of your contacts there? Contacts should automatically sync to gmail unless you changed the default settings.
I've use sms backup to send my text to my gmail account, also there's g-trial that allows u to back up sms, mms, contacts, etc... Now if u can't currently get in your phone it may be too late to do that backup, let t mobile walk u through it, if u have some super important stuff that u need, go to xda or t mobile forums, one of the experts may be able to help you.
Nandroid comes automatically with Cyanogen Recovery. When u boot in recovery mode, before wiping data and applying sdcard Update.zip, u need to click on that nandroid option to backup current. So if u ever want to go back to how things currently are, That's a life saver. I just installed Cyanogen v4.1.6 when I saw it seemed a little slow, i saw i'd have to reinstall all my apps, and i didn't off top see any enhancements I booted (power and home key)and did the "restore latest backup" and boom I was back to 4.0.1! I had to reinstall a few programs but not all. I think 4.0.1 is the most stable, I think they say some apps like youtube, pdf viewer, and the camera aren't working in 4.0.4? i'm not sure if that's just a couple of people having that problem or everybody. But, 4.0.1 is working great for me. I'm not sure what is the most stable version of Hero.
MAKE SURE U GET THE CYANOGEN RECOVERY IMAGE BEFORE ROOTING, AND BEFORE WIPING AND APPLYING FROM SDCARD UPDATE.ZIP, MAKE SURE YOU DO THE NANDROID BACKUP, for extra comfort you can also download G-backup and Mybackup from market to save your applications, messages, etc.... to sdcard, gmail or online.
We all know what's best for us, I don't knock that. But, you do know rooting will make regular task faster? I once said the same thing, I didn't even care about apps2sd, tethering or any of that shyt. I didn't see the real purpose, but when I rooted it felt like I had just bought a new phone! I have 5 screens full of dope widgets, a better keyboard, themes, For some reason my 3g was horrible before the root, now it's much better, 80% of the youtube videos would bring up some error, I did hard resets and everything, rooting has fixed that problem. There's just way more settings options when u root your phone. Who knows when t-mobile will send another update (I think they said 1 more update near the end of the year or early 2010), Cyanogen has updated 2 or 3 times since I rooted 2 weeks ago, lol.