Given another Target Y value and model obtained from data, finding the values of X's(X1, X2 and X3) in the model

HI All,

I am Having a data set with values of X’s regressions and a Y dependent output.

Based on data in excel for X’s and Y, a regression model is formed.
Let’s assume the equation is somewhat like Y = a+bX1+cX2+d*X3 obtained from regression analysis.
My requirement now is given another value of target Y finding the values of X’s(X1, X2 and X3) in the model.
I will be thankful for kindly guide how this can be achieved in Ms-Excel with the given data and model found.