Q: black screen

First, try to reset the phone by holding the sleep and home button for about 10sec, until the Apple logo comes back again. You will not lose data by resetting.

If this does not work, set it up as new device, explained here:

How to back up your data and set up as a new device

Try not to use the backup, in case the problem is software related and your backup data might be damaged.

If this does not bring your screen back, you'll have to get it serviced:

Apple - Support - Service Answer Center

Thank you Ingo2711 your tip saved my day, my iPhone4S came back to life resetting

I have mine for 1 month now. Never dropped in the sun or dampness. I had to plug into computer and it reset. It happened twice in 1 day. I'm diappointed because it must be a hardware issue. We should not have to reboot a brand new friggin phone!

Thanks ur suggestion has helped me.

My Iphone5s is back to life what a relief.

Thank you!

I now have my screen back..Yet it's telling me there is no sim card installed?