Q: does reinstalling mavericks wipe your hardrive of all pictures and videos?

Not unless a problem occurs. Back your data up before proceeding.

(136206)

That you have no backups here is a big problem — hard disks and other storage devices can fail catastrophically, and at any time.

Computers can be lost or stolen or damaged, too.

Always have backups.

As for your question:  The administrator password can be reset with physical access, and without a reinstallation.

The keychain passwords are encrypted with a password, and will be inaccessible without that password, and there's no recovery for that — you'll have to start a new keychain.

And no, the existing data on the disk won't be effected here, unless you choose to erase the disk, or unless there's a corruption or other failure with the reinstallation.  Or a problem with the password reset.

But unless there's little of value stored on the system, always have a backup.  Or two.

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