Unable to factory reset iMac without utility box

Please read the following user tip and restate your question/problem in detail: 

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If you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Recovery Mode. This makes it act as a wired keyboard as will insure a successful boot into Recovery Mode.

Plug a USB keyboard into the iMac and then re-try the Recovery key commands.

Without the barest of information such as what model year iMac, version of Mac OS, if you are using a wired keyboard or not or anything else there isn’t a thing we can do to help. We are end users like you, we are NOT Apple. Apple is the forum’s hosts but they do not read or participate in these forums.