Windows 7: Missing D Disk

Hi, i wanted to remove my new os that were kept in D drive and i delete the volume as instructed by tutorial here. But when i reboot i lost my old OS (which were genuine) and my D disk were gone!How can i got my disk back? (79gb of space were gone)

Please provide a link to the tutorial you followed.

Also, please post a screen shot of your expanded Disk Management window. To open Disk Management, press Windows key (wavy flag next to left Ctrl key) +r, type diskmgmt.msc and press Enter or click GO. Make it full screen.

See here: How to Use the Snipping Tool in Vista - Vista Forums (says it's for Vista but also works with Win 7).

Once you have the image saved, click on the Paperclip Icon next to the Smiley Icon. In the Manage Attachments window, click Browse and navigate to where you saved the image and select it.
Click the Upload button.
Close the Manage Attachments window.
Click on the Paperclip Icon again and select the image you uploaded. It will be placed in your post.