Install language packages and stmaryrd.sty in ubuntu Linux 

The stmaryrd.sty file is part of the texlive-math-extra package. Try installing the package and see, If that doesn’t solve the “File not found” problem. 

Package babel Error If even after package “texlive-math-extra package” its showing error like this You haven’t specified a language option.
 
Undefined control sequence
Undefined control sequence
Undefined control sequence
LaTeX Error: Missing \begin{document}
LaTeX Error: File ‘stmaryrd.sty’ not found

Then in this case this Solution may help you:- Open the terminal in Linux and run.  

# sudo apt-get install texlive-science