One of the most common reasons for getting a "404 - Component not found" error on your Joomla 1.5 front page is a missing default menu item.
To resolve the issue, make sure you set a default menu from your Joomla admin area > Menus. Choose a menu item and set it as default by clicking the Default button at the top right menu.
In our Joomla 1.5 tutorial you can find more information on how to manage your Joomla application.
If you have problems resolving the issue yourself, ask your host for assistance. SiteGround provides the best Joomla hosting and such requests are handled with ease.
Joomla is a powerful software that is easy to work with once you have the right host to support you. Before you lose any more time with the wrong host, check out the hostlantern Joomla hosting offer.