What could cause me to have a total cholestrol level of 238 and LDL of 138? I'm only 20. Can stress cause it? Or whatelse could?

High Cholesterol. Stress can aggravate it but not cause it. More likely genetics play a role, add to that lifestyle such as diet, activity level, general health & stress.
Find and Fix Causes. See your physician. Several inherited and acquired conditions will affect lipid levels. If such conditions are found they should be treated while starting diet, exercise and lifestyle changes. Appropriate lipid and lipoprotein targets will depend on your cardiovascular risk level. In many cases additional tests of LDL and HDL particle number will be needed to ensure you have reached your goals.