The eternal 1st question: Do you have your logo source files?
Is the first question we ever have to bring when approaching any kind of development. And the answer most of the time is “of course” followed by an email with a medium sized PNG at best or more likely a blurry-tiny JPG.
This is usually followed by another email explaining how what they sent me is actually a photo of the logo, perfectly usable for the most basic needs but not of much help for any professional design work.
The source files or Arts of your logo are the blue prints of your brand, they preserve the original design details and colors with 100% fidelity. Even if you stretch your logo to cover a football field.
Think on them like the plans of your home, you are not bringing only a photo of your house when you are consulting an architectural job, the architect will ask you for the plans. In the same vein, most designers will ask for your source files.
This is about technical issues
In the not so distant past the source files were critical for any kind of print job, and more than indispensable on large format printing.
And that is still true, but now with the ever increasing resolutions and pixel densities on screens, we need big size and high resolution images of your logo for screens too.
It is always important to remember the purpose of the logo and branding in general: to unify a set of elements (graphic, semiological, typographic and chromatic) to compose with them a single element.
This unified element (your logo) must be reproduced in a wide variety of media and technologies, some dating centuries ago some as new as 5 years old, and the logo must look exactly the same in all of them, ever.
If you don’t have your logo source files each designer will have to redraw the logo and accessory designs when needed, at your expense.
It hurts the uniformity of all your communications because you are under multiple interpretations of how your brand should be portrayed.