What version of Premiere Elements are you using and on what computer operating system (including 32 or 64 bit) are you running it?
Please give more details
...they appear on the timeline will not play...
Where do they not play?
a. playback of the rendered Timeline in the Edit Mode Monitor after you click on the Monitor's Play Button
b. playback of the export of the Timeline to a file saved to the hard drive or burned to disc
The answers are in the details.
Looking forward to your follow up.
Not a direct suggestion, but some links to help you learn... ALL links because you did not specify a version
Online User Guide http://help.adobe.com/en_US/premiereelements/using/index.html
-Page to download current PDF http://helpx.adobe.com/premiere-elements.html
-Previous versions http://helpx.adobe.com/premiere-elements/archive.html
Importing Video http://forums.adobe.com/thread/1065281
-and project settings http://forums.adobe.com/thread/1112086
Saving & Sharing http://forums.adobe.com/thread/1137128
-Sharing to DVD or BluRay http://forums.adobe.com/thread/1137645
-Sharing for Movies http://forums.adobe.com/thread/1051093
-Sharing for Computer http://forums.adobe.com/thread/1058237
Steve's Basic Training Tutorials... steps are the same for several versions
-start at http://forums.adobe.com/thread/537685
Thanks for the follow up with the good news that the issue is solved and that you are moving forward with your projects.
If the problem presents again, please do not hesitate to post and let us know how we can help.
Good that everything is working... and for future reference, below is the information you need to supply when you ask a question, to help the people here help you
These questions below may be for a different product... but the information you need to supply is the same, for the products you use
-Information FAQ http://forums.adobe.com/message/4200840