Hi @Janice_Muindi,
In cases as such as these, it is best to check your PHP error log for messages there. If unsure of how to do that, please see here: How do I find my PHP error log?
Feel free to post error log messages here once you’ve had a chance to look at them, as this will help community members here on the forum to better understand the issue that is occurring on your OJS instance.
-Roger
PKP Team