Do you use more than one browser? Or more than one computer? Your Bookmarklet needs to be installed separately on every computer and every browser you use. For example, installing it on Firefox will not automatically make it available on Internet Explorer. Just sign in to Clipparoo on the new computer or browser, and go here to install the Bookmarklet.
It's also possible that your links bar in your browser was hidden or rearranged. Check to see if your Clipparoo Bookmarklet is hidden under a "more" arrow, or if your links, favorites or bookmarks toolbar is turned off.