How far can i go back to file back taxes? How can I get my old W-2

You can file taxes back as far as you have access to the needed information and the forms.

The law gives taxpayers who fail to file their income taxes three years to submit a return and claim a refund. The three-year countdown starts on the original due date.

You can request a Wage & Income Transcript from the IRS

What you should know when requesting previous year W2 forms from the IRS:

• The IRS keeps copies of past W-2s (and all tax documents under your Social Security Number) from the last 7-10 years.
• The W-2s are not available from the IRS until one year after they were filed.
• You will need to fill out Form 4506 (be sure to write clearly and sign).
• The service fee is $50 for each request. Checks can be made out to “The United States Treasury”.
• The address to send form 4506 and check to will be listed on the second page of the form. Be sure to send both the form 4506 and check to this address.
• You will have to wait up to two months (or perhaps longer) for the IRS to process your request and send you the copy of your W-2.
  
  

https://ttlc.intuit.com/replies/3301607

Ok? but how can I file my 2016 w2 and 2015??

Please the TurboTax FAQ How can I get a copy of my W-2? for information on obtaining your W-2's. 

i want to know how i can file my old taxes too

@newyork1337  You can use TurboTax software for PC or Mac to file a return for the 2018, 2017 and 2016 tax years.  TurboTax does not support tax preparation for years prior to 2016.  Refer to the following TurboTax FAQ for additional information and instructions on filing:  How do I prepare a prior-year tax return? - Community

Can I file my back taxes with turbo tax

I have my w-2 paper work

@Shelly52 Yes, you can file back taxes with TurboTax. Here's how: How do I prepare a prior year tax return?