Q: osx reinstall disk locked

is there an icon with a lock on it?

click it

use your admin/pass

btw:

Can you select the disk on the Desktop then press COMMAND-I to open the Get Info window. At the bottom panel what is shown? You can make a screen snap to post here:

To post screen shot do this:

1. Press COMMAND-SHIFT-4 which will change the cursor to crosshairs.
2. Hold down the mouse button and use the crosshairs to select the part of the screen you wish to capture.
3. Release the button and the image will be saved to your Desktop.
4. Click on the Camera icon in the toolbar of the forum message editor.
5. Drag the image onto the Choose File button and click on the Insert button.

One trick I have come across for the problem:

Startup from your Recovery HD. After the Utility Menu appears select Terminal from the Utilities menuitem in the screen's menubar. Paste the following at the Terminal's prompt:

     mount -uw /

Press Return. Quit the Terminal then restart the computer.

Did you by chance turn FileVault2 on at some time to encrypt your drive? If so, you may need to open Disk Utility first while booted to your Recovery HD, select the drive and enter the password of any user you allowed to unlock the drive when you turned on FileVault2. Then you should be able to reinstall OS X.

You have file vault enabled. You must first use disk utility to enter the password and then install.

You need to enter the disk utility when your in recovery. Select the hard drive from the left panel it will be greyed out or shadowed - from the file menu at the top choose unlock drive.

When you erased the hard drive how did you format it? Might be you didn't pick the right options and thats why you see no disk.

No just go back into disk utility and format the drive again - guid partition - os x - journaled and try to reinstall. check erase option.

How to reinstall OS X on your Mac - Apple Support

If the Partition option is grayed out look to see if the Erase option is active. If it is, then click on it. Be sure to choose the out-dented entry from the Disk Utility device list before clicking the Erase button.