Your Apache has not started and as such will not serve the file you are asking for, test.html.
Try and start apache with the bat file and paste back here any error messages you get:
leave the console window open if it starts and try your http://localhost/test.html
again as this is the correct address if your test.html
file is in the \htdocs\
If your apache won't start then copy and paste the error message here.
You copy and paste by clicking on the little icon C:
in the top left of the console window and selecting 'Edit'
and use the menu items you find in that presented menu.
BTW did you make any changes to any of your configuration files?
There is a help section in the XAMPP Control Panel, although a bit thin, it is worth reading to set up your CP to start the services or the XAMPP components correctly.
Also what OS and XAMPP version are you using?