Indexing Spotlight

Question

Then I start my IMac (I have Yosemite 10.10.2) Spotlight then spends about about a hour re-indexing, During this re-indexing period I can use Spotlight and look for the items (indexed items) but afterwards (after that the indexing ends) it is still not able to locate any of the files on the disk.

Answer 1

Step 1
These instructions must be carried out as an administrator. If you have only one user account, you are the administrator.
Triple-click anywhere in the line below on this page to select it:
syslog -F '$Time $Message' -k Sender mdworker -o -k Message Rne Norm -k Sender mds | tail | pbcopy
Copy the selected text to the Clipboard by pressing the key combination command-C.
Launch the built-in Terminal application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad and start typing the name.
Paste into the Terminal window by pressing the key combination command-V. I've tested these instructions only with the Safari web browser. If you use another browser, you may have to press the return key after pasting.
The command may take a noticeable amount of time to run. Wait for a new line ending in a dollar sign ($) to appear.
The output of the command will be automatically copied to the Clipboard. If the command produced no output, the Clipboard will be empty. Paste into a reply to this message. 
The Terminal window doesn't show the output. Please don't copy anything from there.
If any personal information appears in the output, anonymize before posting, but don’t remove the context.
Step 2
Enter the following command as in Step 1 and post the output:
mdutil -as 2>&- | pbcopy
You can then quit Terminal.
Step 3
Launch the Console application in the same way you launched Terminal. In the Console window, look under the heading DIAGNOSTIC AND USAGE INFORMATION on the left for crash reports related to Spotlight. If you don't see that heading, select
          View ▹ Show Log List
from the menu bar. A Spotlight crash report has a name beginning in "mds" or "mdworker" and ending in ".crash". Select the most recent such report, if any, from the System and User subcategories and post the entire contents—the text, please, not a screenshot. In the interest of privacy, I suggest that, before posting, you edit out the “Anonymous UUID,” a long string of letters, numbers, and dashes in the header of the report, if it’s present (it may not be.)
Please don’t post any other kind of diagnostic report, such as hang logs—they're very long and not helpful.