After re-installing the package (agricolae), I call the package and the result as following:
library(agricolae)
Error: package or namespace load failed for ‘agricolae’ in get(Info[i, 1], envir = env):
cannot open file 'C:/Users/x9-999/Documents/R/win-library/3.5/Matrix/R/Matrix.rdb': No such file or directory
>
Please notice the directory of agricolae; is: C:\Users\x9-999\Documents\R\win-library\3.5\agricolae.