The application will still be stored unchanged on your hard drive and all that has happened is that you have removed the "short-cut" to opening it. Depending on which operating system you are using (Windows something, Ubuntu/Linus, Mac OS, etc.) you should have access somewhere to a list of resident applications (as bookbinder said, for example in "Start" in Windows). Find Abiword and open it (usually this will simply by clicking on it). Once it is opened you should then have somewhere a way to mark it on the taskbar. Post the name of your operating system here (including version) and someone will advise you specifically regarding it.