$\displaystyle y''+2y'+5y=\left\{\begin{array}{cc}1,&\mbox{ if }

t\leq t\leq\frac{\pi}{2}\\0, & \mbox{ if } t>\frac{\pi}{2}\end{array}\right$

where $\displaystyle y(0)=0, y'(0)=0 $ assume that $\displaystyle y$ and $\displaystyle y' $ are continuous at $\displaystyle t=\frac{\pi}{2} $

I don't know where to start this problem. any suggestions?