what are you doing, attempting, you never said that.
my guess this 10 year old PC has VISTA,
and you have the vista DELL disks still after all thoughts years>?
if you do page 42 covers ever step in that process.
http://www.manualsdir.com/manuals/600855/dell-inspiron-1545.html?download
lets say you said, I have W7 install media,
on DVD or USB stick
w7 does not fit on any CD ever.
so if you dont have the optional DVD drive there,
then its hopeless there, and then the stick USB works.
what you do is boot to the windows 7/10, usb stick you must make on a working PC, the ISO file is free at microsoft.
but you must buy a COA key later (30 day time)
w7 must be bought up front, no free loads at MS for W7.
the first PC sold this model can not boot to USB
so you must update bios to version A14
per
as DELL tells you here
https://www.dell.com/community/Laptops-General/Unable-to-boot-from-USB-in-Inspiron-1545/td-p/4219287
next time tell the helper what you are doing or attempting
we cant guess the 1million things folks do to any computer made.
I see the BIOS updates are now long gone too. on this old PC.
just so you know, that.