Normally, to restart a synchronization engine (as you probably know), log on to the box where the synchronization engine process should be running, and fire up the an RTC Eclipse client.   In the clearcase synchronized streams view, select the team/project area containing that synchronized stream, right click on the synchronized stream, and select "start synchronization engine".

But you said: "Because of the restart I have no synchronised streams in the view".
By "view", I assume you mean the cc synchronized stream view?
But the synchronized stream info is in the RTC database, and therefore whether or not the sync engine process is running should have no effect on what you see in the cc synchronized stream view ... that should have all synchronized streams that have been defined.   One thing to check: Have you selected the team/project area that contains the synchronized stream you are interested in?   The sync stream view only will show you synchronized streams that belong to the team/project area you have selected in the sync stream view.

Note:To avoid having to manually do this restart, you'll want to add the synchronized engine to the "auto-startup" list for you synchronization host machine.  That is described in the help topic "Starting the Synchronization Build Engine Process": http://pic.dhe.ibm.com/infocenter/clmhelp/v3r0/index.jsp?topic=%2Fcom.ibm.team.connector.scm.cc.doc%2Ftopics%2Ft_sync_builder_start.html