In my Eclipse:
Windows -> Preferences -> General -> Startup and Shutdown -> Workspaces:
And the "Prompt for workspace on startup" is checked, but anytime I start Eclipse, it does NOT ask for workspace to open.
Why is that? Please help me! Thank you!
Try starting Eclipse with eclipse.exe -clean. You can also manually edit Eclipse files, but better use the supported run argument. As I already commented - this is suggested here, but you seem to have skipped it and went straight for the second answer :-)