4s phone screen is frozen Screen on phone is frozen diplaying wall paper and slide to unlock.  Voice recognition works, but cannot enter passcode with frozen screen.  How can I get into the phone, need pictures.  Have not backed up phone.  Can pictures be retrieved from SIM?
Sometimes the homescreen seems to hang on iOS7.  Sliding up for the camera, or down for notifications centre etc can work, but sliding across to unlock doesn't.  It's very annoying.  You need to restart the phone to get past it.  You can either:


hold the power button until the slide to restart message appears, and if you can slide there then do that, or...
hold the power button and home buttons together until the Apple logo is shown.