In ArcMap, the user clicks the Search button and nothing happens (no search window opens or appears)
This can happen if ArcMap fails unexpectedly and the search window location stored in the user's profile gets corrupted, or sometimes when the user moved the search window to another display and that display is no longer connected. (The search window may come up, but who knows at what screen address!)
Here are a few fixes to try, in this order. Close ArcMap, try the fix, and restart ArcMap and see if it fixed the problem.
1. Reset Normal.mxt in the user app profile: Resetting your ArcGIS application profile
2. Reset the entire Esri folder Resetting your ArcGIS application profile
3. Delete any DefaultDomain_Path folders. (Note, this may also help if the search window appears, but doesn't find anything)
a. Open Windows File Explorer
b. In the file path box type: %APPDATA%
c. Click the up arrow to go up one folder
d. Open the Local folder, in that open the ESRI folder (you should now be at: C:\Users\username\AppData\Local\ESRI)
e. Delete any folders with a name starting with: DefaultDomain_Path...