Can I file an amended tax return through Turbo tax if the original tax return was prepared and filed by another service provider?

[VolvoGirl]

You can but it might be a hassle and you won't be able to efile it.  For what year?

To amend a return you did somewhere else or you don't have the original .tax file, you would first have to fill out Turbo Tax like you are doing the original return and pay for it. You have to recreate the actual wrong original return. Then when it matches each line that you really filed you have to tell Turbo Tax you will mail it so it thinks it was filed. Then you can amend it.

For the current year you can use the online version by first recreating the original return exactly as filed. Then pay the fees and say to mail it and print it out so it think you filed it. Then when it matches every line you can amend. How to Amend the current year
https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-federal-tax-return-curr...

Or you can buy the CD/Download Desktop programs here,
https://turbotax.intuit.com/personal-taxes/cd-download