I lied to my girl friend about my age and I was with her for almost 2 years and now she discovered that and she break up with me what I shall do to let her come back
I love her so much and I want to marry her

So how old are you, how old is she, how old did you SAY you were and why did you lie?

A lie is a lie. And a lie that perpetuates throughout an entire 2 year relationship is hurtful, it is a preview of more lies to come, and it may not be reparable.

Right now she's angry, and I don't blame her. You have (hopefully) apologized and asked for forgiveness. You must now let her forgive you or not, and accept it as a consequence for your actions.

My age is 28 and her age is 31 I told her before that I am 30
When I date her first time I do not expect that we will be together so I just said any age
Then I loved her and I get afraid if I told her the truth I will lose her

Well you were right, she found out you lied for two years, and dumped you. Why would she take a long time liar back? I don't know but you better leave her alone for a while. She may forgive, and miss you. She may not.

Let her cool off, and see.

When she looks at you, she is seeing a person who looked her in the eye, and lied to her without qualm, for two years. Even worse, it was about something stupid. She must be wondering what else you are lying about and hod big it is if you managed to hid this for two years. It is really up to her to make a decision about continuing your relationship, and you need to give her the space and time to do so.

I think you should have told her the truth as soon as it turned serious instead of waiting two years later. Now, like Tal said you just have to let her cool off and see. Hopefully, everything works out.