Unfortunately, there is no simple formula for calculating a general risk of ruin based on actual trades. It is a nasty mathematical snarl that needs to be solved with a computer, only simple and fairly unrealistic cases such as the symmetric risk of ruin and Kelly risk of ruin can actually be reduced to simple arithmetic.

There are computer programs which calculate risk of ruin, including some free applications and spreadsheets available online, you'll just have to do a search for them.