Unfortunately I don't know how the cache disappeared, nor where Chrome was originally downloaded from.
Chrome was reinstalled from the official Google site
On my Windows 7 Starter netbook the facility to clean the Google Chrome cache is not shown - whereas this does appear in the program on my Windows XP PC.
Since cleaning the Chrome cache is important, is there any way of making Wise Disk Cleaner do this, rather than having to use the Chrome tool?