ている場合じゃない【ているばあいじゃない】

ている場合じゃない means "this is no time to be doing ~". It goes after the て-form of a verb, and it tells someone – often yourself – to stop what they are doing because something more urgent needs attention.

ばあい場合 is "situation", so the literal sense is "it is not a situation for doing ~". The verb is in the ている form because the complaint is about something already going on.

Talking to yourself

Said to yourself, it is a push to get moving. A sentence of what you have to do next usually follows.

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じゃない is the spoken form. In writing and formal speech it is ではない, and to someone you speak politely to it becomes じゃありません or ではありません. In casual speech ている shortens to てる: みてる見てるばあい場合じゃない.