SQLServer 2008R2 SSAS NOT STARTING

  I would request you to follow the below steps incase SQL Server 2008 R2 Analysis Services fails to start again.

1.       Change Logon On for SQL Server 2008 R2 Analysis Services in SQL Server Configuration Manager from NT logon to Local System

2.       Clear the Application log in the event viewer without fail as this is very important.

3.       Restart SQL Server 2008 R2 Analysis Services using SQL Server Configuration Manager

If you are new to SQL Server Configuration Manager then refer the following article Overview of SQL Server Configuration Manager to know more about SQL Server Configuration Manager.

Hope that Helps!