I efiled with an unknown company last year my 2018 taxes and still have never received my refund

Then you have to go back to that company to see if it was filed and accepted or ask the IRS if they got your return.

Do you think 2018 never got filed?  Do you need to file it?

To do a prior year return you have to buy the Desktop program here,

https://turbotax.intuit.com/personal-taxes/past-years-products/

You will need a full Windows or Mac to install it on.

Or If you have a simple return You can fill out the blank forms for free.

Here is the IRS 2018 Form 1040

https://www.irs.gov/pub/irs-prior/f1040--2018.pdf

And instructions  https://www.irs.gov/pub/irs-prior/i1040gi--2018.pdf

2018 Tax and EIC Tables https://www.irs.gov/pub/irs-prior/i1040tt--2018.pdf

IRS 2018  Schedules 1 thru 6 (only if needed)

https://www.irs.gov/pub/irs-prior/f1040s1--2018.pdf

https://www.irs.gov/pub/irs-prior/f1040s2--2018.pdf

https://www.irs.gov/pub/irs-prior/f1040s3--2018.pdf

https://www.irs.gov/pub/irs-prior/f1040s4--2018.pdf

https://www.irs.gov/pub/irs-prior/f1040s5--2018.pdf

https://www.irs.gov/pub/irs-prior/f1040s6--2018.pdf

Don’t forget your state.  And you will have to print and mail your returns.  So be sure to attach copies of your W2s and any 1099s that have withholding on them.  You have to mail federal and state in separate envelopes because they go to different places.  Get a tracking number from the post office when you mail them for proof of filing.