Try a Hard Reset - Press the Power+Volume+Camera keys until the phone vibrates Then release the power button but keep the volume and camera keys pressed for another 5-6 seconds.
Data loss without warning.
I need am adapter for my C6 to take a micro sim as a backup.
Suggest that you read Page 13 of User Guide:http://nds1.nokia.com/phones/files/guides/Nokia_C6
"Important: Do not use a mini-UICC
SIM card, also known as a micro-SIM card, a micro-SIM card with an adapter, or a SIM card that has a mini-UICC cutout (see figure) in this device. A micro SIM card is smaller than the standard SIM card. This device does not support the use of micro- SIM cards and use of incompatible SIM cards may damage the card or the device, and may corrupt data stored on the card"
Symbian specialist until 31/01/2013 with interests in Maemo & MeeGo but an aversion to Windows!
2012-11-21 11:40 - edited 2012-11-21 11:42
Some badly designed adapters can get stuck in the phone. The best adapter is the part of a normal SIM which remains when a micro-SIM has been cut out. Get an unused normal SIM and have somebody with a cutter cut a micro-SIM out of it. Most phone retail shops can do it for you. Then fit your micro-SIM inside (it will fit tightly) and use it on your C6. It won't know you are using an adapter, trust me.