Personal tax time barred returns

I have erroneously forgotten to file a personal tax return for the last 3 years and according to all the articles i've researched - my filing is now time barred. 

Firstly - is that true. I dont have a tax liability - but would like to file it all anyway as I've made investments which I've sold in consequent years. 

What is my recourse? What can be my next course of action. I'm not a tax avoider - but am ignorant on the local tax laws which I've been completely misguided upon in the past. 

Thanks