Using "donde" rather than "dónde" after "estar"

Question

In today's translation exercise - "Something’s not right in my new home" - I had to scratch my head really hard to understand why the phrase "objetos que no estaban donde los había dejado" had rendered "donde" without a tilde on the 'o'... Yes, it is a relative clause - but here, the 'connecting link-word' is "que" rather than "donde" > (" ... objects [which were] not where I had left them").
 
Initially, I thought I should be able to compare it with sentences structured round the verb "saber", for example: 
"No sé dónde lo guardé"
and
"No sé dónde viven" -
[sentences given in my dictionary and grammar book].

Inma Sánchez · Accepted Answer

Hola David
With relatives like this is always tricky to see the difference, is it a relative (no accent) or is it an indirect question (accent)? In this particular sentence, because there is no noun right before it´s more difficult: 
"...objetos que no estaban donde los había dejado"
First of all, we have two relatives here: 1. que (referring to objectos, "= los cuales no estaban" 2. donde (referring to the "place": no estaban en el lugar en el que yo los había dejado" 
To know that this is a relative and not an interrogative, we need to see if the "donde" is "describing a place or asking for a place":
donde los dejé means “(the place) where I left them.”
It refers back to a place implied by “estaban / no estaban” (their location) --> relative, no accent
In your sentences with "no sé dónde..." there is a question: 
No sé dónde lo guardé.
¿dónde lo guardé? -> I don't know
No sé dónde viven
¿dónde viven? -> I don't know
There are cases where it's really difficult to differenciate and there is disagreament between grammarians, for example in this type of sentence where there is no noun implicit but it is still a relative:
No sé el lugar donde se celebra la fiesta.  (relative, el lugar en el cual...)
No sé dónde se celebra la fiesta vs No sé donde se celebra la fiesta.
In these last two, I could take it as a relative or an interrogative:
I don't know where the party is celebrated.
I don't know the place in which the party is celebrated. 
Relative or Interrogative?   - there are different opinions.
Saludos 
Inma