Macro to sum values from another Workbook with Multiple Sheets - vba

Question

I am working on a project that requires me to sum multiple values in another excel workbook.
The other Workbook contains, say, 120 sheets. I want to take a certain value from each sheet, and sum it along with the rest. The cell reference for all the 120 values is fixed, for example J3.
Another thing worth mentioning (maybe) is that the sheet code names aren't organized (i.e. Sheet 1 all the way to Sheet 120), there have been several sheets added/removed in between.
Right now I'm getting
Run Time Error 424 Object Required
Sub SumProject1P()
Dim Project1P As Workbook
Dim reserves
Dim WS_Count As Integer
Dim i As Integer
Dim V As Variant
Set Project1P = Workbooks.Open("FILE PATH")
WS_Count = Workbook.Worksheets.Count
V = Workbook.Worksheets
reserves = sumrange(Workbook.Worksheets(V).range(Cells(1, 8)))
End Sub
Function sumrange(range)
summ = 0
For i = 1 To WS_Count
summ = summ + reserves
Next
reserves = summ
End Function
I hope to receive feedback and input.

Answer 1

Here you go
Sub SumProject1P()
Dim Project1P As Workbook
Dim reserves As Long
Dim WS_Count As Integer
Dim filePath As String
filePath = "Enter you file path"
Set Project1P = Workbooks.Open(filePath, ReadOnly:=True)
WS_Count = Project1P.Worksheets.Count
For i = 1 To WS_Count
If Sheets(i).range("J3") <> "" And IsNumeric(Sheets(i).range("J3")) Then
reserves = reserves + Sheets(i).range("J3")
End If
Next
MsgBox "Total of all sheets :" & reserves
End Sub

Answer 2

You are getting the object required error because you are not using the Worsheets.count function to any object.
Your code:
Set Project1P = Workbooks.Open("FILE PATH")
WS_Count = Workbook.Worksheets.Count
You need to use this function for Project1P object.
Set Project1P = Workbooks.Open("FILE PATH")
WS_Count = Project1P .Worksheets.Count
Santosh already gave you the simplest way. Still if you want to do it by using Function then try the below.
Sub Sum()
Dim Project1P As Workbook
Dim WS_Count As Integer
Dim i As Integer
Dim V As Variant
Set Project1P = Workbooks.Open("File path")
WS_Count = Project1P.Worksheets.Count
sumrange (WS_Count)
End Sub
Function sumrange(TotalSheets As Integer)
Dim reserves As Integer
For i = 1 To TotalSheets
If Sheets(i).range("J3") <> "" And IsNumeric(Sheets(i).range("J3")) Then
reserves = reserves + Sheets(i).range("J3")
End If
Next
MsgBox "Total of all sheets :" & reserves
End Function