Can you use spotlight to search for Disk Utility? Is spotlight giving you any result? If yes, between search box (it will appeard when inside spotlight you will type Disk Utility ie) in spotlight and TOP HIT you have an option called show all in finder. When finder window will be open, find Disk Utility, click on it once so it will be highlighted and then use CMD+I (i for India) and check under General section what is appearing under "Where".
If nothing found, then you might try to download ML 10.8.5 Combo Update: http://support.apple.com/kb/DL1676
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