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Very rare that you are the first to encounter something like this, so always search first.
See BlackBerry FAQ - BlackBerryFAQ
and the two articles on JL_CMDER. You will need to wipe the device, then resinstall the operating system.
Either use the operating system provided by your carrier for your model, or see the "latest OS" thread for your model here on the forum and get the latest official release.