I need to take data from a report in a txt format and enter it into
excel. The portion of the report I'm interested in looks like this:

3532 10:10 12:15 310
13:22 14:19
14:37 15:18 449

2312 09:01 09:32
10:22 11:11 543
13:12 14:20 310

The data I'd need is any row with data in the 4th column but I need to
know the number in the first column too. The problem is, the way the
data is grouped the rows won't all have data in that first column. In
the example above, I'd need to somehow note that the 3rd row is valid
data and is associated with the value 3532. And, the last 2 rows are
associated with a value of 2312.

There are many other rows in the report that I don't care about. If
rows 2 and 3 had 3532 in them in that first position and the last 2
rows had 2312 in that first position I'd have no problem. I have no
idea how to do this. Anybody else?

Here's one way.

With your data in columns A-D, enter these formulas.
In E1: =A1
In E2: =IF(A2="",E1,A2)

Then copy E2 down as far as needed.

Then you can select column D and use
Data Filter Autofilter (Nonblanks)
to view only the rows you care about. The associated first-column value is
in column E. (Hiding column A might avoid confusion.)

Adapt to suit your needs.