ONN model ONB13AV004. How can I use it to control a Magnavox TV?

That make model number is a mess. You need 'make' and numerical model number only.

Here are your codes

https://myuniversalremotecodes.com/onn-dvd-universal-remote-codes/

Usually you can but replacement remotes, but this is Walmart's own bargain basement brand from China, made at the lowest cost point and the highest profit. Quality is not a consideration!

https://www.google.com/search?q=ONN+ONA19DP005+remote

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Set-up (Programming) procedure is too much to type in here, and is not practical and it will differ brand-to-brand remote controls. If you wish to get more; check the sites linked here. The site has set-up code list & set-up procedure to many popular brand remote controls. The site has general set-up codes to check with TVs and other devices are given, in the order of the 'device's brand name list' in alphabetical order. Set-up code list to many brand remote controls also is given. Pull up older posts. Search the sites by type in the brand name to your device in its search box at the top right part of the display window. It will help you to find the document easily......
http://electro-medical.blogspot.com/

Joyce you should find code at the links below.
http://codesforuniversalremotes.com/3-digit-universal-remote-codes-for-tv/ 3 Digit Universal Remote Codes For TV Codes For Universal Remotes

4 digit GE universal remote control codes with code entering instructions

[PDF]Instructions - ONN Universal Remote Support

myonnremote.com/.../ONB13AV004%20Manual%20Version01.pdf

Mar 28, 2014 - will retain the codes you have programmed for up .... TV/DVD Combo, you might need to set up one ... Point the remote at the audio receiver,.

Faq - ONN Universal Remote Support

myonnremote.com/onn-faq.asp

How do I manually enter codes for my ONN Universal Remote? ... (You haveapproximately two seconds after the device shuts off or begins playing to lock-in the code.) ... so if you need to start the search again, it will pick up where it last left off.Missing: duraband ‎ht395 ‎reciever

RC: Durabrand codes one for all (Page 1 of 2) - Remote Central

https://www.remotecentral.com/cgi-bin/mboard/rc-one4all/thread.cgi?...

May 4, 2006 - 15 posts - ‎9 authors

Set-up (Programming) procedure is too much to type in here, and is not practical and it will differ brand-to-brand remote controls. If you wish to get more; check the sites linked here. It has set-up code list & set-up procedure to many popular brand remote controls. One among it has general set-up codes to check with TVs and other devices are given, in the order of the 'device's brand name list' in alphabetical order. Pull up older posts. Search the sites by type in the brand name to your device in its search box at the top right part of the display window. It will help you to find the document easily.
http://electro-medical.blogspot.com/

0018 0044 0094 0154 0170 0190 0308 0320
Try these codes. If you wish to get more details; check the sites linked here. It has set-up code list & set-up procedure to many popular brand remote controls. Common set-up codes to check with TVs and other devices are given, in the order of the "device's brand name list" in alphabetical order. Pull up older posts.
http://electronicshelponline.blogspot.com/
http://electro-medical.blogspot.com/
http://remotesearch.blogspot.com/
http://electrohelponline.blogspot.com/
Search the site by type in the brand name to your device, in the "Search box at the top right of the display window" to see the set-up codes to your device, with different brand remote controls.

I need a TV code for a Sanyo please

If you have a remote control you should be able to access the "atuoprogram" feature within the setup menus. This will look for all active channels and place them into memory. What model is it?